I think your tour idea is awesome. I completely get why you want your specific goal, to where your family lives. It's tremendously satisfying to cover a distance to something that's important to you, under your own steam. But entire days spent being uncomfortable has a way of being very demotivating. I haven't done many long bike tours, but I've done some long-distance hiking, and days with bad weather, or boring surroundings, or with some minor injury really sucks the joy out of things.

Trailers are terrific for hauling stuff. But pulling a trailer is hard work, and I wouldn't count on doing that all day unless I had to.

You're obviously the most motivated, so anyway you can wrangle that you ride the whole distance, and anyone else just joins you every now and then, or at a hotel for the night, sounds like a good idea. You'll ride that much faster and more comfortably if you're on your own, without hauling stuff.

Let us know how it works out!