Hi goofballracer,
I do not live in San Diego any more or I could be of some additional help.
Before doing anything inside get it water tight. The siding is .019 aluminum. Unless it has big dents in it or holes I would reuse it. The main problem with the aluminum shinned campers and trailers, is the factory used the easy to clean up and cheap putty tape on the joints and ends. Unscrew the strips of trim starting at the bottom and work up with the siding if it needs to be replaced.
If the siding is good remove every piece of trim, windows and doors. The same for the roof. Scrape all of the caulking off and remove the items going through the roof. Replace the putty tape with polybutal tape (the better cousin of the cheap putty tape). Clean the remaining with solvent to remove all of the oil left on the surface from the putty tape.
When the surfaces are clean put the new 1' X 1/8 " polybutal tape on the pieces that you removed. Use all new screws #8 size X 1" at least. Do not over tighten at this time. Only tighten until you see a little of the polybutal tape squeeze out. Stop and let the tape sit for a day in the warm sun. Go over every screw when it is warm tightening just a little more. When finished tightening, take a putty knife and genteelly cut against the edge of the trim down to the metal siding (using care not to cut the siding). Cut with one hand while pulling the excess off with the other hand. This should take care of the sides. For the roof do the same but follow up with "Vulkem" 1 part Polyurethane sealant over the exposed cut polybutal tape and all screw heads.
Note; Polyurethane is the best product that will last 25 years in the sun, rain and snow. It is messy to work with but it works better then any other product for this type of application. It is moisture cured. If you need to press it into a corner, hole etc. spit on your finger and it will not stick to your finger. Put water on your finger and have fun getting it off. If you need to get it off use paint thinner right away.
Now I do not know it they are still around but try Aladdin Supply in San Marcos for the aluminum. They can order by the pattern you have in limited colors. You may need to have it painted when your done to match colors.
If you do this the correct way you will never have a leak problem again. Note; bullet holes, trees crashing through the roof are not meant to be included in the prior statement.
