Oops, sorry I didn't look closer at your pictures. Holes are ok as I didn't see how you insulated the floor. I prefer foam but insulation of any kind is a must. I would reconsider your door location and large storage (bathroom?) area in the front. That's a lot of floor space to take out of a house your size. Site is screwed up and won't let me modify my last post. Look up Lip Ripper Guy's posts, you'll get 100's of good ideas. That hole in my bathroom/storage wall is where I put a tv, it takes up zero space from inside house.
Got brakes? If not, get em. Your holes look a little close to the wall by your wheel boxes, you might have to trim the sides of your hole covers. I did the same thing, not a big deal. Why all the room up front with o hole? That’s a great spot to slit up between a door & hole And a bathroom. Be sure the door hinges toward the front. Good start.