Good questions and thanks for the reply!
1. Just an old, beater Alaskan camper, the pop-up hydraulic one. A rental is certainly a good idea, especially if I can find a make/model that I might want to purchase.
If you have an RV rental place near you, take the time to rent one or two if you can and take a long weekend trip.
You can tell a lot about your needs in just a few weekend trips
2. We would likely do one to two week trips. Maybe a longer trip, once or twice a year.
Since you will be towing it often, look for something with good axles, brakes, and tires. One of the cost cutting tricks that manufactures will do will put minimal at best components under their trailers. For example, my trailer has a GVWR of 5500# and has 2 #3500 axles under it. Some trailers with the same GVWR are equipped with 2 2500# axles and expect the last 500# to be factored in tongue weight. I think you will have much better luck with something overbuilt a little than something right on the edge from the beginning.
3. No plans for guests. Wife, me and a couple killer Boston Terriers!
Take a look at the rear bath or rear living room models. They usually work well as couples trailers and have some extra sleeping space in the dinette and/or sofa if needed every once in a while.
On a side note, our current Jayco is a double over double bunkhouse with the queen in the front. This is our first bunkhouse and we purchased it since we have kids traveling with us. I have actually used one of the rear bunks several times and they are quite comfortable. My wife snores like 25 pigs in a barn and, as anyone married more than 15 min knows, every once in a while you just need a good nights sleep. I think that if we would buy another trailer, even when the kids are grown, we may consider another bunkhouse just for this reason.
4. Full kitchen and a full bath, no tub needed.
Many trailers don't come with a full range/oven anymore, just a cook top and convection microwaves. Our current one is that way and I can tell you that we don't miss the oven one bit. Also consider an outside kitchen if the model you are interested in offers one. Ours has one and I find that I cook out there more than inside. Just frying bacon outside in the morning saves so much mess and smell inside the trailer.
5. I try to buy one time. LOL Thats why I'm considering a new truck. The RV thing is kind of new with us, but has been appealing for a few years and as we get closer to retirement, it seems like a real good option for the things we like to do.
There are many good manufactures and some not so great. Also, there are many levels of trailers offered from those manufacturers. I don't want to start a brand war since we all have our favorites. But, shop around. There are reasons why the same floor plan is offered by the same manufacturer at different price points. I'm not telling you that you have to buy the absolute most expensive. But, you will quickly find that there are reasons why entry level trailers are so cheap.
Whatever you buy, opt for the enclosed underbelly, largest tires and axles offered, and best cabinets and interior construction you can find in your price point.