I think your bunny looks thin. I raised show bunnies for about 10 years and you should not be able to feel their spine poking up. It should be kinda like cats ribs. So you can feel it when you are looking for it, but it shouldnt be a prominent feature. cute little bunny. Is he a dutch? We mostly raised mini lops and holland lops. We have had our fair share of new zeleand (the traditional big white rabbits) though. If you have any questions feel free to pm me!
Did you know you can box train a rabbit? once they go in a place they will never go anywhere else, so if you put the box in the rabbits cage and they go in it a few times then you can put the box in a room with the rabbit and he will go in it assuming you show him where it is.