94 V6 Overheating when pulling boat

I'm having problems with my 94 Rodeo (126k miles) overheating when pulling my boat. The temperature creeps up from about 1/4 of the way on the gauge to 3/4 with the AC on. When I cut off the AC, the temp drops, but never fully settles back down to 1/4. I have installed an auxiliary transmission oil cooler and had the radiator acid cleaned about 30,000 miles ago. That helped some, because at one time I was having the same problem ascending hilly terrain without towing. But the problem keeps rearing its ugly head no matter what I do or how much I spend!

From reading other posts, about this subject it seems that I may need a new radiator and am leaning towards a heavy-duty 2-pass radiator ($300). Has anyone had this problem and intalled a heavy-duty radiator? If so, did it solve the problem? I've spent a bunch of money and the problem never fully goes away.

Thanks for your help!

you got it. If that is the orginal rad I would for sure swap it out.