Whenever I get that deer in the headlights feeling I will focus on whatever little project I am doing at the moment, get that done, mark it off the mental list. If I'm still confused, I'll find another part of the car to work on and finish that ... before you know it things are getting done
Not sure what your working condition/space limitations are ... but worse case scenario .. cinder blocks, 4 x 4s, lumber shims, bottle jack. Build columns of cinder blocks in each corner of the body ( either side of rear wheel wells and by firewall body mounts), make it wide enough to roll the chassis under it, use it to take the weight off the rotisserie, inch by inch, one corner at a time. Then unbolt the rotisserie, remove it, roll the chassis under, inch by inch, corner by corner lower it as close as you can get it to the frame and still live room to pull the 4 x 4 cross supports out ... the last few inches you can probably rig something up with a floor jack.
The jacking and lowering can be done 1 1/2" at a time on each corner using a bottle or floor jack and some 4 x 4 "extensions" .... if going up, jack up 1 1/2" ... slide a lumber shim under the 4 x 4 cross support ( on top of the cinder block column) ... repeat on each corner till it's high enough .... do the reverse to lower it.
I built a weird body caddy with a metal frame work and trailer jacks in each corner to raise and lower the body.