I can easily get 40 for 5, so I'm in (best recent max 50 for 3 reps)
Specific rules on form? i.e. must be below chin to lockout? Do each 5 reps have to be reset from the bottom (i.e. below chin/at clavicle) or can we pause at lockout and bounce in the hole? obviously no leg drive allowed, locked knees.
Personally my form is usually quite tidy, but gets messier towards heavier sets - more lean back, more bend in lumbar spine. Personally I'd be happy for rules to be pretty loose and allow any amount of lay-back, so long as bar goes below chin and is locked out, and knees remain locked throughout.