I agree that the dedicated bracket on the tongue is a pain, but it is fundamentally different from using the coupler, and has advantages in mover design. At least one style of bracket for the AC-5
(there appear to be at least two styles) looks like it could go ahead of or behind the WD system brackets: although ahead would put the mover in conflict with the Andersen chain (or conventional WD spring bar) location, that doesn't matter because the chain (or bar) is not there when the mover is used.
I think the question is whether or not there is any real estate left between the propane tanks, WD brackets, storage box, and whatever else might be on the tongue. Also, the further back (from the coupler) the mover bracket is attached, the more traction the mover will have (due to increased load carried by the mover.
With any dolly, I would want to check that I can swing the dolly 90 degrees each way from straight to manoeuver without hitting stuff such as the tongue jack with any part of the dolly.