Hi,
I have owned a 1989 40 DC (series 1) for about 12 years now. We are not interested in selling but it has been a very good boat for us and how we use it. The 40 DC has a nice aft queen birth although the 2 heads are a bit on the small side. its a easy boat for 2 to handle and maintain. Ours has only been in fresh water in the Great lakes then freshwater lakes in central Canada. These type of boats are pretty much rust free. If I was going to do the loop I think I would like a slightly larger Hatters like a 52'. The extra room may be worth it if you can afford it. The 40 DC could handle the loop but may be a bit small for living on full time for many months. The 40DC's engine room is a bit tight for working on unless you are fairly small and light (which I unfortunately am not).
Buy the best boat you can afford.
Soft goods (carpets, flooring, blinds / drapes / valances / mattresses / bedding / furniture / canvas) are fairly easy and not too expensive to replace. The big ticket items are the mechanical systems (main engines, transmissions, generator, HVAC, plumbing, charger / inverter, solar, batteries, and the state of the hull.
Good luck in your search. Try to find a well maintained fresh water boat if you can.
Mark
Lake of the Woods
1989 40DC (series1)