Take a look at my log, that’s very similar to I do. Old Guy Doing 5/3/1 - #1295 by OTHSteve On my 3’s week (days 3 and 4 of my current cycles. since I’m doing 2 whole body days per training ‘week’), instead of going for max reps on my last set, I stick to 3 reps, then do 1-2 heavier joker sets of 3 reps to get my fix of heavy weights in. I do this to because like you, I sort of feel like I haven’t worked hard enough unless I push some heavy weight, but it keeps me from hurting myself while doing it since I’m doing sets of 3 instead of singles. I also never do a set that I’m not sure I can make. I don’t ever miss a rep while doing 5/3/1. All bets are off when I’m doing strongman event practice though, I don’t know the implements well enough to be 100% sure what I can do until I try it.
This works especially well in the early stages of a cycle when my training maxxes are normally significantly less than my true max. Once I get ten cycles in or so, I’ll have to start backing off because my training weights start becoming a more significant fraction of my true max. About the time I start being unable to hit 10 reps on the final set of 5’s week is when I have to start backing off on the joker sets.