Boondocking tips on the way from Denver to Alaska

x2 on Church's book; it's very helpful and complete and about as enjoyable to read as any book of that sort might be.

The Yukon territorial parks are all $12 per night (and all include free firewood), payable either using an iron ranger or with a prepaid voucher that can be purchased at various locations. The main advantage of the voucher, at least that I can make out, is that the iron ranger can't give change.