You do have a fair point there. I think for now I'll keep it in my mind and figure out if I can get 33' or 35's with 4.7's before September. I wish I could work overtime but I work on a farm. No such thing.

It isn't that a rig with 31's can't make it through, it just takes a lot of skill to do so, skills that you do not currently have, and wont be able to get by finding 33's or 35's.

If the trails out at Gold Bar are rocky and similar to the Rubicon, you should be running them every day you have off between now and September, learning how to pick the right line, how to stack rocks to get through the line you pick, how to get back on the line once you get off of it, learning how to follow a spotter, throttle control, keeping track of rocks as you lose sight of them, getting used to being in an off camber situations, etc.

Dual cases/lower single case is still your best bet with you determined to run the trail this Sept.  I know you are on a budget, and overtime isn't possible with your current job, you might consider a part time job at a fast food restaurant to fund the cases, where there is the will, there is usually a way.