The aluminum siding is fine. In fact, I do use it without water on there too. I find if you're washing and use Awesome to get the streaks off, it doesn't work as well if the surface is wet than it does when dry.
The logos are the main thing to watch out for...for you the big F+R Sunline logos and the side Solaris logos. If you can, watch out for the striping, though it shouldn't hurt it as much as it can the logos since it's all solid color.
EDIT: One more thing, don't let it sit on the fiberglass either. I don't think it would be an issue on the new shiny stuff, but with the old stuff when it gets chalky, if the Awesome drys on there, it will leave a yellow mark where it was sprayed / dripped down. That's hard to get rid of.
I still remember the one day when we brought the 2251 home. We all worked on washing it with Castrol Super Clean (before we discovered Awesome) and while spraying it on, I remember watching as it dripped down, it became red as it crossed the striping. Not good. So we had to be extra careful for the rest of the job.
2007 T-286SR Cherry/Granola, #6236, original owner, current mileage: 9467.8 (as of 5/26/19)
1997 T-2653 Blue Denim, #5471
1979 12 1/2' MC, Beige & Avocado, #4639
Past Sunlines: '97 T-2653 #5089, '94 T-2251, '86 T-1550, '94 T-2363, '98 T-270SR