trailer tongue

Depends on the load you are carrying. If it's a light load I'd use an extra long ball mount or fabricate one. Those extensions suck to use. Too much slop.
If you're towing heavy you could extend the tongue...maybe. It will make it a PITA to hook up because you'll be reaching under the camper. Then you have a good chance of jamming the tongue up in the camper at something like an uneven intersection or any ground with a drastic elevation change.

I have an 11.5 on a pickup. It needs a four-foot extension. I choose to stretch my trailer tongue because the physics are so much better.
Lots of people say if you do that you'll hit the camper on a steep angle, but you'll bottom out on the ground in the same place with an extended hitch. Neither is well suited for extreme off-roarding but in many thousands of miles I've never had a problem like that.

With only a one-foot trailer tongue stretch needed to clear your camper I think it would take a pretty extreme angle before you had a clearance problem.

Another benefit of stretching your trailer tongue instead of using a hitch extension is it makes one less thing you have to do every time you load or unload your camper.

You always gain here and loose there.
Shorter extension puts less stress on truck hitching and helps with truck weight distribution, but when trailer tongue goes under camper, crossing a ditch can bring a disaster even if corners clear on jack-knifing.

One foot won't make a huge difference either way. But generally speaking, you will be better off with a longer trailer tongue than a a hitch extension. The tongue weight will be applied closer to the truck's axle which is better both structurally and dynamically.

Yah, I had the same thing come up pulling a little SxS 6x12 open trailer.

I have a 24" extender/stinger but the catch is as you go out in length, the less ball weight it can carry.
Ex:
I have a Flatbed on the Truck Cab Chassis. Camper on that required a 24" extender. Tongue weight at the flat bed was reported at 700lbs (not sure if that is correct) so with a 24" stinger it's cut in half to apx 350 lbs tongue weight. (I think that is too much but?? I was less so didn't worry about it)

The point being that the further out you go, the less tongue weight which is obvious, just think of hitting a bump and think about the swing up and down.

There is a formula for calculating the amount from the original hitch to the the extender.

Other option is as noted above, call torklift for a Super hitch depending upon your towable.. or a local shop that can do the calculations..

Hope that helps..

which is better structurally

Which is better for what? The truck or the trailer. I would go with a longer tongue for the trailer if all other things were equal. If you extend the tongue of the trailer be certain that the tongue extension can handle the trailer's weight. Otherwise there is always Torklift that makes a truck receiver and an extension that is strong and works.