Wanted to make a post about a pretty simple model 46 backhoe that i made, just in case anyone is looking for ideas when trying to make their own. I sized the height of it so that I could keep the backhoe pins (ones used to avoid leak down, not the subframe pins) in to keep the hydraulic cylinders from leaking down on the arm. I was able to just use the bucket curl to relieve enough pressure on front subframe pins to be able to get the backhoe off. The dolly holding the sub frame arm (at the point where the subframe pins go) is simply a harbor freight dolly with a few pieces of scrap wood screwed into it to hold onto that crossmember on the sub frame to keep that small separate dolly from sliding around.
The main backbone of the dolly is a butcher block type piece of scrap I got from my dad, the other stuff is just scrap wood chunks left over from other projects. I think this should be at the right position so I can just back up to the connection points, connect hydraulic lines, fiddle with the bucket curl a bit, connect pins and be good to go. We will see how it works in practice the first time I try putting it back on though!
The dolly casters I ended up using: Amazon.com: 4 Swivel Casters 1600Lbs Load Capacity, Heavy Duty Plate Casters with Safety Dual Locking Casters Set of 4 with Brake: Home Improvement
They seem decent so far but I'll come back and update if I find they get flat spots or anything else undesirable.