Had a bit of a play with Dolly today. Made some ramps out of a plank and loaded up. Even with straps on, the front wheels did start to kick out, as Chris mentioned. So a rethink in order. I'll put it on backwards.
Slight problem with that. My plank ramps rested on Dollies wheels, with a block underneath to stop them being pushed forward. Worked fine going up forward, but the C-81s rear ag' tyres could not get grip. So some cross pieces added. Also chains added, that looped round Dollies wheels, to stop the ramps being pulled off.
That done and loaded up without any problem. Ratchet straps secured tractor wheels to Dolly hitched behind the C-121 and time for a test. Ahh! But! I'd done all this halfway into the workshop. Time to try reversing and turning round in the yard. Here the problem was the front wheels of the towed tractor. They had a mind of their own. So a simple technique was devised. Low box and low revs enabled me to dismount and turn each steering wheel as required.
Once turned round and out onto the lane. Test was successful I'm pleased to say. The towed tractors wheels, after completing a turn, do take a while to fully come back in line. But this doesn't cause a problem.