Well I basically do what you do. I don't have dog hair to contend with, but a lot of road dust on the garage from all the crap that accumilates on the cars from when they cinder the roads when it snows.
I just sweep the area where my "tent" will be. Use small bungie cords to hang some of those blue tarps with eyeletts in them. I just use the rails for the door as places to attach. I don't go for those 6 foot deep miror finishes, and this works well for me. Keeps the overspray from getting all over the windows and walls, and it's easy to take down/setup. Cost was nothign as I already had the tarps, and bungies .