I've heard of guys doing it. Drain the fluids, take out the battery (and all the loose junk in the trunk and interior). The one guy made brackets that bolted on to the unibody without removing the bumpers. He had pictures of installing an exhaust system with the car laying on it's side.
Mav1970 All the steel I bought was 4 feet of 2" x 3" Mild steel and 8 feet of 2 " x 2" Mild steel. What I also did was I bought a 3rd engine stand for the steel. It is much cheeper to buy another stand than buy the steel by itself, also the steel in the stand is exactly the right size to extend the uprights. If you do not extend the uprights the car will hit the floor when on its side. Yes the car is well balanced and spins real easy. I am in the middle of writing a how to article (Holidays have slowed that down) Coming soon though
For the last year or so I've been collecting steel from the scrap pile at work for a rotissore. Have most everything I need now and hope to have it built end of summer. Just too busy to spend a lot of time on it right now, daughter getting married in August, yard and garden work, building a new deck and a small pond, new patio doors the list just keeps growing. Anyway it is going to be my own design and there will be a unique twist to the ones you have seen before. When it's done I will be sure and post pics. It's going to be great.
I got a little side tracked on the car with a 4 door daily driver and I am about half way on the write up. I will try to finish soon.