1. WD-40 is a lousy lubricant and even worse as penetrating oil. Acetone mixed 50-50 with automatic transmission fluid is the old standby.
https://www.engineeringforchange.org...netrating-oil/ recommends cooking oil instead of ATF; cheaper and works a little better. Ed's Red is popular with firearms shooters:
http://forum.accurateshooter.com/thr...lvent.3837877/ and it also shows results of a semi-scientific Drexel University engineering school test. Oil of Wintergreen is highly spoken of but I've never tried it.
WD-40 stands for the 40th Water Displacing formula tried. It's a Water Displacing chemical that was never intended as a lubricant.
2. Better get a good air compressor and a rattle wrench for removing the rusted in nuts and bolts.
3. Buy a selection of nut breakers to remove the nuts the rattle wrench doesn't.
4. Buy the proper personal protective gear: full-coverage eye protection, heavy gloves, face shield, dust mask, etc.
5. Get to know the hard points that allow you to jack up an Airstream without tweaking it an ruining it.
Probably a bunch more that I can't think of straight off the top of my head.