I agree that preventative maintenance is the key to reducing problems and extending the life of the trailer, but I think that also means taking on some responsibility for it yourself, which means up-skilling yourself and research this stuff carefully as you are doing to assess their quality and potential for problems.
About 16,000 lbs more or less gets you into full-time quality unit. Quality is heavy, IMAO.
I worked at an RV rental repair dealership for about 3 months. We had entry level quality motorhomes, mostly gas C's and some gas A's. I got them road ready after a rental and I would average about 4 a day. We had, for example, these pressed wood doors, which we were constantly repairing, and coming up with creative fixit solutions. We called them junk (c..p), but others would love them I'm sure. But I'm guessing that each rental basically was used about as much in one year as others might use them in about eight years, so we saw them under extreme usage conditions. Some people were kind and some kicked the crap out of them.
So, you could say I'm very sensitive to quality vs need for repairs vs on the road time, and whine time waiting in line at dealerships...er wine???
By the way, I'm retired and my goal was to get hands on experience, buy the right tools, and see how things work, and then I got out of there.
Loved my air compressor for all kinds of get it back on the road stuff. The goal was to fix it just good enough to get it out the door. The magical air compressor tools.
As you might guess, even though I'm very good at fixing entry level, I'm not likely to buy an entry level RV/tt/5th, and I'm very likely to buy a premium used dp this year, but yes a seneca and a 5th/truck have not disappeared from my mind. Wife's input is critical.