For that size, I'd opt for one of 3 tires. If you're on 7,000 lbs. axles, pay attention to the maximum load carrying capacity of whatever you get.
I don't have a toy hauler, but I did have the same size tires and opted for the Maxxis m8008. They were good until I started maxing out my axles (year-long trip/rented out my house). That's when I came to the realization that my tires had 3,420 lbs. of carrying capacity individually but were on 7,000 lb. axles. I also paid for a weighing where they weigh each wheel individually and found that 2 of my tires were at 3,400 lbs. and a third was at 3,500 lbs. I upgraded to a higher rated tire.
The other thing you have to watch for is how much space you have between your wheels. For me, I had less than 2" of space. Which meant I had on wiggle room on tire size and couldn't increase the outer diameter at all. If I could, there were a lot of options in load range E with the higher carrying capacity. Just something to pay attention to.
So anyway, for recommendations:
1) Maxxis m8008 (max load of 3,420)
2) Goodyear Marathons (unsure of max load)
3) Goodyear G614 (max load of 3,750; but make sure your rims can handle 110psi)
I have also read quite a few recommendations for Saliun tires. They have a higher carrying capacity, but are also larger than my existing tire.
I opted for new rims + tires (17.5" commercial rims and Continental HTL Eco tires), but I'm not sure how they would handle being aired down.
My only issue with going to LT tires is that generally speaking, their carrying capacity is less than an equivalent ST tire in the same size.