You have a few options. You can find some durable spacers, such as rubber mats, to put underneath the plates. These can even be other plates as long as you are careful about setting them down. If you have a rack that allows for pins to be set around the mid-shin, you can use those. Lastly, you could buy some Rogue Hi-Temp plates and leave them at the gym. A pair of 15 pound bumpers are $50. A pair of 25 pound bumpers are $83. Perhaps the gym would be willing to foot some or all of the bill with you. It wouldn't hurt to ask.