Lets not disCUSS unschooling home schooling!
If when you plan to return to where you currently are, look at the local district you are in, they may very well have an HS program installed. The district I live in has a LARGE, ie 450-500 student campus for HS students, along with the one my kids are in. Moving my daughters to the district operated HS program was a godsend to them, especially my younger one. She has jumped some 3 grades farther than she was with EX unschooling them! Older daughter still has issues, twin sons overall are doing pretty good.
The owner of a local brokerage, just got back from 2 yrs of a pacific rim sail HS'ing his twin daughters. They spoke at a Jeanneau owners get together a few weeks back with the girls. They are glad to be back in school, but ALL enjoyed the experience.
Out of all this, FOLLLOW some sort of plan, do NOT ust go along figuring it out day by day, ie "unschooling" at least for my kids, experience, I will whole hardidly say, it sucks! one reason for divorce from Ex! I will also note, I am NOT a real fan of HS'ing because of my experience, BUT< I also have seen enough parents that took the job above and beyond on how they did things. to realize, it is the person doing the teaching, time spent to plan etc that makes HS'ing a good experience. WIth me working 12-14 hrs a day to support a family of 6, my time was very limited in most ways.
Be smart in how you go about doing things, and it will turn out well for your kids on trips like this. We did a few land trips for a month or so here and there that were/are unforgettable, as we did them during non summer months, and got to see more because of lack of crowds.
marty