I don't think a mini rotisserie has to be all that complicated, it's light enough if you make it reasonably strong it'll be fine.

I was worried about plans etc but in the end just made it out of scrap steel lying around mostly.

Use square to pickup the front subframe bolts on the crossmember another square section to pickup the shock mounts in the rear (i welded washers so it fitted in nicely) a piece of pipe to skewer the mini and you've mostly just the stands to go.
Slightly larger pipe for the pivots and I used the same slightly larger pipe to create lock rings (captive nut welded on).

The stands use some square, one slightly smaller than the other makes it height adjustable rotation locking is performed by a old Landcruiser vented disk rotor and a pin.

Here's a picture :

I put three castors each end on later to wheel the mini around on.