Great to see another new Scamp owner.
You will be amazed at what a difference a good cleaning and polishing will make, cost is low, payoff is high. And best of all you can use it while you make progress.
Our Scamp is about the same age and was in about the same condition as your pictures show last fall
when we got it. We also had massive amounts of silicon caulk which is just nasty and evil on fiberglass.
The seam tape comes off pretty easy, blow dryer for a little heat can help, and new tape can be purchased from Scamp online store.
The ensolite (elephant hide) walls can be cleaned with LA Awsome and a scrub brush. I also got good use from a set of auto detail brushes from a big box store. Stiff but small enough to get in nooks and crannies. We had mildew, looks like you had someone that smoked in the trailer. Bar Keepers friend was also used inside ours.
Some folks caulk the seams after removing the seam tape. Some even paint
the ensolite. Now that ours is cleaned I'm just going with the seam tape.
Bar Keepers friend was suggested for aluminum and fiberglass cleaning and it worked great with a rag on fiberglass (removed all that black) and detail scrub brush or plastic pot scrubber pad on alum. The green scrubbers can leave scratches on the fiberglass so a little care is in order to not scrub hard on the FG with them. I think there are softer scubber pads that might be a good choice, maybe white?
The decals can be purchased from the scamp store if desired. As can the curtain rod brackets and much of the other hardware.
Polish for the aluminum such as Nevr-Dull is readily available from auto parts store, I liked to follow that with Semi Chrome polish which leaves a protective film on the alum. Note aluminum polish creates black residue, masking tape to protect white fiberglass will save you having to clean the black off the white trailer.
TSP available at big box and hardware stores to wash, rinse well and follow with the Red Max #3 available at Lowes. See this thread for more info. Check this out NOT Poliglow...Time will tell..
All I can say is that Red Max applied to a really clean camper makes the trailer look like new. We owe a debt to the brave camper who first gave that a try on their FG egg.
Fiberglass polish such as StarBrite works really well on the inside fiberglass. Cleans and leaves a protective polish behind.
Parts like the curtain rod brackets, and plastic plumbing and electrical
covers, even the decals for them are available at the scamp store.
You can cruise through this thread where I sort of tracked my progress through the refurbishing process. Others have posted answers to my questions there that I found most helpful.
Refurbishing my 77 Scamp