I've had some success by deadlifting for a heavy set only every other Friday. On alternate Fridays, I pull one moderate set of 8. It's enough to feel like work, especially after heavy squats and bench, but not a rep max. Your percentage offset will vary - start modestly. You could riff on this theme too and offset for a set of 5 or something else. I just like the variety of a slightly higher rep range and by extension a lighter weight of course.
I got the idea from the more advanced plan of alternating rack pulls and haltings. Maybe it'll leave you fresher for your hard DL set. For reference, I'm on a HLM plan.
Remember you can also choose a hard set that's not a five - say a triple.