Waxing class c

I would use two 6' steps side to side and build a scaffold using a new 2X10x8 or two of these boards screwed together if over 200lbs. I'd position it 6" away from the tip of the cab. This way you wouldn't have to lean too far over, compromising the stability of the scaffold. If stability is a concern, I would screw or mount the far side leg bottoms, or feet of the ladders each to a piece 2x6x4 laying it flat, extending the extra length of the boards away from the front of the rig. This will eleminate any tipping concerns. I built a setup like this year's ago when I rehabbed the cabover on my older 1st rig that suffered delamination from water damage.