My house is on the small side, and I'm too lazy to train in a cold ass shed / too cheap to heat it, so when I bought it the first thing I did was knock out the master bedroom closet, sister the floor joists that were less than great, drop down 2 layers of plywood, and lay stall mats down. Used some barn door hinges, and 2x12s / 2x10s / 2x8s /2x4s and built a bed that folds up. Now the bedroom has more than enough room for my squat rack / glute ham bench / dumbells / barbell / plates, and plenty of space to use them too (other than ceiling hight is still insufficient for standing overhead presses and my head grazes the ceiling when I chin). Cheap to do, and having a rack+chains in the bedroom is handy for more than just squatting. I did something similar the last apartment I lived in but there wasn't room for the GHR (which at that time I had to keep in the living room with my heavy bag and speed bag).
I do recomend using some brackets on the 2x4s that hold the matress up if you go that route though instead of just screws. I've busted a few of them fucking too hard.