I am not too sure what the upside is for the child in a plan like that. Most families have enough to contend with, without hitting the road.

The trailers out there are in no way really designed for continuous use. For one thing, they are mostly designed for sitting. You want a peaceful trip, a recumbent position is your best bet. Suspension would be a good idea. We had a chance to get whatever stroller we wanted but settled on a modern version of the old fashioned pram. Never regretted it over ten years of babies in prams. These old designs just float over the bumps, and something with as effective suspension would be great for a road trip. I could imagine a purpose built design for touring. I would like to see something built well enough that a helmet would not be required. I don't see a baby wanting to rid in a helmet all day.

A number of makers have 2 wheeled trailers that are only one kid wide. That might be an advantage in performance terms, and in the ride being narrow enough to avoid road edge problems. As bad as the rumble strips are another hazard around here is new road edges where the tarmac, is soft. It is hard to tell where the trailer will sink in, as it all looks equally hard.

One of the things that perplexed me about my kids is that even up to something like 8 or 10, they were not interested in looking at stuff out the window of the car. I think we have a romantic view that kids are nearer nature, and that means that they will enjoy just passively watching beautiful scenery. But they were not like that. They loved drawing and the outdoors, and had well developed aesthetic senses, and so forth. But scenery watching was an acquired taste. The point being they did not want at any time in their lives to be carted around for hours, sight seeing. They liked camping, and doing stuff in the outdoors, not being dragged through it. Probably they would like a scenic overlook for a few seconds, and then they would start clambering over the rocks and scratching picture into the sand. Most kids need much smaller bites of stuff than their parents. Whatever happens, no two are alike, and it will not turn out as you plan it to turn out. Basically you have a lot to learn.