First, welcome to the Forums!
One very good resource, which is outside the forums, is vintageairstream.com. Look in the Airstream Restoration Resources section, and you will find an exhaustive list of supplies and suppliers. You may also check out the "stickies" in the Airforums general repair forum home pages--there tend to be many frequently referenced articles in these, and you might find just what you need.
You will discover that when it comes to working on these trailers, there is rarely only one "best" answer for what product to use, or even how to use it. For example, your topic of "insulation alternatives" will get you several threads that debate the relative merits of everything from pink fiberglass to rockwool to various types of reflective bubblewrap to sprayed in foam and nano-tech microspheres. It is up to you to decide what is best for you based on what you want to spend, and what may be available to you.
Another hint is that if you do a "google" search from outside the forums with key words like "rivet tools airforums" you are likely to get better results than you will by using the search function that is built into the Forums.