first up...is the garage free of cars as residual fumes from car engines exhausts etc can cause respiratory problems in buns.
wire floor on cgaes are cruel but still widley used in some places..it makes their feet sore and they cannot get to their cecal pelelts to eat them if they too drop through.
i owuld definatly give a litter tray a plastic hi backed one is best..solid flooring is best for buns..you can use wood covered in remnants of lino flooring.....and self adhesive vinyl floor tiles from cheap shops.
having ocd how do oyu cope with the pets!!
bunnies apprecaite having a tray with some form of cat litter like yesterdays news in the bottom with maybe a fine straw covering and mounds of hay..they do enjoy eating and pooping at the same time