Where to do archups and GHR if you workout at home?

Title says it all really, I dont have a vault or anything to do archups, and VERY rarely have a training partner. So what interested and cagey ways have you guys come up with?

Appreciate your time.

GHR, by sticking my feet under a couch. I generally throw a pillow down for my knees and insteps to rest on.

Archups can be done with the use of a door pullup bar and a swiss ball. Perhaps flexing your foot into a wall and hanging over a swiss ball.

I've done back extensions on a chair on it's back on the floor. It's not comfortable but it works. If you have a bench for bench press/situps/etc, you might be able to figure something else out. I also used the decline pushup bars on my total gym for GHR and laying facing down and the floor for back extensions.