I own several M101A2 trailers and have sold two or three. The 16" rim with 8 lug bolt pattern has many advantages over many of the other rims found on older military trailers and even over the M1101 with HMMWV tires and rims.
The 16" Rims with 8 lug bolt pattern 6.5" with 235 85R 16 tire are universally obtained at Walmart, Tractor supply at a very reasonable price. The wheel & tire combination are $125-$170 and if you choose a more aggressive tread pattern, those 16" tires are also available at a reasonable cost. The same 8 lug bolt pattern matches my goose neck trailer and car hauler.
A much easier solution is to mount your pintle hitch on a variable height 2" adapter, so the height of pintle can be easily adjusted to make the trailer sit level. A B&w Tow and stow adjustable height 2 5/16 ball/ pintle is what I use behind my Jeep Grand Cherokee to tow the M101A2 trailers or a trailer with 2 5/16 hitch. I took a trailer to North Carolina and back this summer and barely noticed it behind the Jeep for the 3200 mile journey.
I added a bull dog square tube trailer jack so that it makes it easier to load the trailer on the Jeep, my dually, or any other standard tow vehicle.
There are lots of military trailers, trucks etc that need modification to make them more user friendly, The M101A2 whether a Kasel or other make is perfectly functional as is, without any modification. Just my opinion.