We have a Ameri-lite ultra lite trailer and love it. That said some ultra lites have weight saving measures that may or may not fit your needs.
Ours is a 3 season trailer without enclosed and heated under belly, less insulation and single pane windows. We are fine if it freezes over night as long as it gets above freezing the next day. Since we don't winter camp, it works for us. Even in the 20s the furnace keeps us warm and only runs 3 times a night.
Some weight saving things have no impact on our camping like the plastic sinks and toilet. We will never know there is OSB in the cabinets unless there is a leak. Our propane tanks are 20 lb instead of 30 lb but we have yet to use one of those in a trip.
OSB in the cabinets is one thing, in the floor is another. Some manufactures use OSB or Luan in the floor and it will eventually sag from use and really give if leaked on. Ours has 3/4 inch ply and doesn't sag even under my 220 lbs +.
One thing I would have liked is larger tanks. 30 gal of fresh water doesn't go far so we take extra and conserve.
For us having the ultra lite means we can have more trailer and not strain the truck as much. It also cost half as much as a nice 4 season model of the same size. Ours seems constructed well enough as it is no pavement queen. We are usually 5-10 miles off the beaten path and NFS roads are rarely maintained well. We cross wash outs, traverse rock strewn trails and ruts to get to those out of the way spots on a ridge.
So make sure the ultra light you pick has the features you need. Replacing a sink or faucet is one thing. A soft floor is a bigger issue.
2011 GulfStream Amerilite 25BH
2003 Ford Expedition with 435w tilting portable/ TS-MPPT-45
750w solar , TS-MPPT-60 on the trailer
675 Ah bank, Trip-lite 1250fc inverter
Sportsman 2200w inverter generator