My first camper was a Lance with almost the same layout (except a Dry bath). I didn't end up creating a lot of memories in it as it ended up having a lot of dry-rot damage. I put $3000 into her before giving up and selling it for something different.
I see that you are working on sealing the roof which is the right place to start. Seal it all and also check the seems on between the roof and the walls (that is where my water damage came in mostly). Also check the skirts at the rear / bottom of the camper to make sure they are sealed well. It is just a piece of plywood that I think had a metal trim piece covering up the leading edge. It didn't fully protect the edge of the plywood from spray from the tires when it was raining.
Lastly, not sure if it matters to you or not but the upper cabinets above the dinette do turn into a bunk, or at least did on mine. A feature I wish I had on my Bigfoot today (apparently it was an option???).
Happy trails and keep the pictures coming!