MYP Towing Square Wheel Setup - prefer to go to 20's

[edgecrusher]

Been looking through MANY threads, but can't seem to find a combined response.

I'm looking to bail on the UberTurbine 21's, and go to a square setup, preferably 20"s. Factors are mostly ride quality, efficiency, and proper loading for towing.

My winter setup is:
Replika R241 Satin Black wheel | 19X8.5, 5x114.3, 64.1, 40 offset
Conti Viking Contact 7 - P255/45R19 XL 104T

I would like to go to something similar for the summer, but 20", and I assume slightly wider tires for load when towing (a boat).

Thoughts on this setup?
Replika R241-2000-65BT+40C641 (20x10), 40 offset
Pirelli - PZero - P265/40R20 XL 104Y

When putting this into PMC Tire (in canada) it says 'doesn't fit your MYP'....

 

[MrJeep997]

The load rating is more than enough on any tires rated for the MYP and there is not much tongue weight capacity so I wouldn't worry about adding extra width (350# only adds 175# max per rear tire.) I tow great with my square 19" setup on MPS AS4+. I probably go over the tongue weight slightly. I haven't yet put the UT21's back on to see how it's different.
Ride quality and efficiency are better with 19" as you will no doubt have already read.