I can tell you to stay away from Juneau. They don't like people and small, recreational motorized vehicles around there.
I do know some people who are 4-wheelers and they go up to Haines in SE Alaska to go 4 wheeling. Haines is a smaller town. While I would not call it isolated, it doesn't have any chain restaurants that I recall and if you have a medical emergency, you are driving to Whitehorse or going to Juneau.
If you wanted to know more about life in Haines, there is a decent book written about it by a local news reporter there. The book is called "If You Lived Here, I'd Know Your Name" by Heather Lende.
Pick it up, it is a good read on life in small town Alaska.
Southeast Alaska has milder winters than the midwest and many days over 90 degrees in the summer.
Skagway is nice tourist town - hopping with 10,000 tourists a day all summer long - and DEAD int eh winter - but you can drive to seattle in 24 hours straight through
or haines is the same but no tourists - those are where you should go.
Nowhere if you plan to wreck the place on a trail bike, they value their land up there and don't want it wrecked!
I have no idea. Why don't you take Google Earth and look at the topography of that state up close.