The problem with "tactical fitness" and other types of conditioning based programs like P90X and CrossFit is the basic lack of understanding of the difference in the nature of the adaptations to strength training and conditioning. Strength training improves conditioning by increasing work capacity, but endurance training does not improve strength. To put this is more concrete terms, at some point doing "Fran" no longer improves your "Fran" time, as you have noticed.
The amount of work you can do in a given amount of time is quite thoroughly dependent on your ability to produce force. A big strong out-of-shape guy can carry more bricks in a 4-hour period than his little skinny runner buddy. Sorry, but we all know this is true. My military contacts tell me that, without exception, the strongest guy in the outfit is the most useful in a jam, even if he's a little fat and has a 12-minute mile. So let's start off by recognizing the fact that work capacity is much more dependent on strength than conditioning.
Strength training produces an increased force production adaptation, the nature of which is "architectural" -- it requires, and thus causes, the construction of new tissue within the muscles, without which increased force production is ultimately not possible. When your squat goes up, the weight on the bar has increased, and your having added weight to the bar sets in motion a series of events that cause the muscles to grow. This process takes a while, but can go on for many years. This is why lifters who take a 5-year layoff are still stronger than runners who have never lifted, and still stronger then they would have been had they never trained. The process of growing new tissue causes permanent changes in the muscles and the neuromuscular system, and even the more transient effects of strength training, like some of the weight gain, are very easily recovered in a short period of time because of the permanent architectural changes that have taken place over the longer time frame of the process of going from novice to intermediate/advanced.
On the other hand, the adaptations involved in conditioning are actually short-term alterations, because they depend on changes in systems already in place -- alterations in enzyme production, membrane function, O2 and substrate transport and utilization, and stuff produced by the cells that does not involve laying down a new mass of contractile protein. These adaptations happen quickly, and go away just as quickly, as you must have also noticed, because they involve far less metabolic effort by the cells. This is why after your strength training layoff your return to CF-type activity -- your "work capacity" -- is much more rapid than the long process by which your strength was built, why your strength decline happens slowly and reverses immediately, but takes longer to return to where you stopped, and why even after the layoff, you're not as weak as you were before you started training.
But your months spent in the intensely catabolic environment created by high-intensity glycolytic work coupled with high volume and low intensity (as a % of 1RM) also decimates your strength training progress by producing high levels of systemic inflammation. Chronic inflammation is the cause of overtraining, and the mechanism involves overproduction of cortisol in an attempt to reverse the inflammatory processes that you keep ramping up every time you do 100 anythings for time. This catabolic effect on your strength is why you're not squatting/pressing/deadlifting really big weights, and why the whole process seems like two-steps-forward-two-steps-back, with no real long-term progress in either strength or conditioning. You cannot adapt to chronic inflammation, and it can kill you by affecting organs other than your muscles, in addition to keeping your squat below 315. A lot of people have noticed this, you included, so this question comes up at every seminar in the Q&A.
My recommendation is that you rethink the process. If you like doing random high-intensity work with shitty technique on the clock, continue to enjoy yourself. But the process of becoming "conditioned", i.e. being able to work at at high HR/Respiration Rate, actually takes about 3 weeks, so you're never more than 3 weeks away from being conditioned. So you can plan accordingly, and there is absolutely no reason to devote 4 months to what amounts to the catabolic destruction of your strength progress. If you are really and truly employed in a profession that demands a broad spectrum of physical adaptation, I'd recommend that you step back from the dogma and analyze your experience in that job: what physical parameter has contributed the most benefit to your ability in the field? If it is your ability to run 5 miles, you'd be in a rarefied profession. If it is your ability to move quickly and move heavy shit RIGHT NOW, I'd say that strength and power (its derivative) is the adaptation of most benefit to you, with conditioning being nice to have but not as crucial as the strength necessary to move you and the heavy shit.
So in the latter case, I'd have you on a strength program 3 days/week and pushing the prowler once/week. You stay in shape, you stay strong, and you're not sore and inflamed all the time. Systemic inflammation is the process that tears down your strength training progress during your CF 'season". The prowler produces no soreness, it preserves your strength progress, and it is a frighteningly effective tool for conditioning. If a need for heightened conditioning comes up on the schedule, change your program a couple of weeks out, but the prowler work will keep you in good enough shape to handle any real-world situation you may encounter in the field that does not involve high-rep snatches done incorrectly for 3 minutes.