Your pinch points for staying under max load ratings is the Frontier gross vehicle weight and the gross rear axle weight.
We travel light, no kids, no pets, no bikes or boats. I've been on the scales a couple of times and i've been under max weights but not by a lot. My trailer is rated at 3,850 gross weight with max axle rating of 3,500. The trailer is also 7.0 feet wide so that gives up living space but keeps weight down.
Having said all that the Frontier handles it really nicely. Plenty of power but be prepared for MPG of 10 to 11 when towing. You will also need some type of towing mirror add-on to really have a good view around the trailer. I went with
These and they are pretty stable.
Because I went with dual propane tanks and dual 6V golf cart batteries I have a lot of weight on the trailer tongue. If I had not bought a weight distributing hitch I would be over the 600 lb tongue weight limit of the Frontier. The WDH shifts some of the tongue weight to the front axle and the trailer axle.
I have the Crew Cab, 4WD 4.0L with automatic. For the two of use this combination is working out very well. Major upgrade from our pop-up camper.
Good luck with your search.