I know there are many ways to put a trailer hitch on the I-match. If I have my rear ballast mounted using my Heavy Hitch weight rack, I can use the 2-inch receiver on that to mount my cart. But if I don't have or want the ballast on there, I wanted a low cost way to connect my cart without removing the I-match. I found an 18" hitch extender on Amazon that works pretty well. For my 10P cart, which is very low, I also needed a ball mount that would drop down a few inches. The extra length of the ball mount put the hitch farther out than it needed to be, so I looked for a way to shorten the hitch extender a bit. (If you have a trailer at a more normal height, matching the tractor's receiver, the 18" extender is the right length already. You can use it with a hitch mount like Heavy Hitch's 3-in-1 trailer tow hitch.)
So I took the receiver pin out and pushed the 18" extender into the receiver as far as it would go. It went in about 5 more inches to the back of the receiver. Then I pulled it back about a quarter of an inch, lifted the end of it up to remove any sag, and then used a scribe to mark new holes on the extender through the holes on the receiver. The new holes ended up reducing the extender's length by about 4.5 inches.
The cart is easily mounted to the hitch. The I-match doesn't have to be up to avoid interference. The red support wheel on the cart can be removed or installed with the cart mounted on the hitch. There's no concern about a heavy load in the back of the cart lifting up the hitch point. (With hitches mounted on the I-match, this could happen since there's no down pressure on the 3-pt.)