I'm not the best person to answer that question as 1. I don't tow and 2. I don't have a 4.6 with 3.73s but I'm going to give you my opinion anyway lol.
The 26' trailer will likely be a tall order for that truck. I think it's all about how much towing you'll be doing i.e. are you towing it to a spot for the summer and leaving it there until fall, or are you going to be putting on alot of miles. The framing of the trailer (aluminum or steel) will also play a large factor in the weight of the trailer which will make a big difference in how much work it'll be for the truck.
If you're just towing it once in awhile, I'd say you should be OK. However, like I said, I'm not the expert.