I also want to buy one of those Werner work Platforms. Waiting til they go on sale is a great idea, but might have to wait a while. I have not seem them at Lowe's and I have asked even online, but just get a deer in headlights look at times. Don't uderstand why they don't carry it as they have most of the rest of the Werner line.
Ok, what I have done and it works, but is usually in the way, but I use it just to get the roof done. What I do is disassemble my Gorila ladder, put one on each end of the car and I slide a 2x12 into the steps. I can adjust either lower or higher as needed. I have screwed (2) 1x1's on one end, so that it does not slide.
Just using what I got.