Good afternoon Harry,
You may want to use caution sanding the aluminum bodywork. In the aircraft world, either chemical strippers or more exotic forms of blasting (dry ice etc.) are typically used for paint removal as for at least some aluminum structures have the surface of the panel has different propertied than the core.
Aluminum typically needs some form of etch before prime/paint. The etch can either be a preliminary treatment in advance of priming or in the form of a self-etching primer.
Eastwood has an article on prep and priming of aluminum (of course featuring their products...)
https://garage.eastwood.com/diy-how-...SAAEgIo6vD_BwE
You may also want to look at
www.Aircraftspruce.com for products intended for aircraft use such as
https://www.aircraftspruce.ca/catalo...clickkey=12575 or more generally
https://www.aircraftspruce.ca/catego.../cs/index.html