Congrats on your new endeavor, or should I say adventure!
The 25 ft AS will tow like a dream - that's a good size to have following behind you!
Take it slow and easy to start - don't forget those narrow roads or bridges tend to crowd you on the RH side of the road, so take care to keep plenty of room there when you see one of those 'Narrow Bridge' signs!
Slow and easy when going into gas stations, parking lots, etc...you'll get the hang of it!
BTW...most all of us here refer to our Airstreams as 'AS' or 'Airstream', not 'Air' - to avoid confusion with other things that have the word 'air', etc...
Have a great time with your new 'Aluminum Tube'