Agreed, we ladies want, maybe even "need", a full length mirror in our Airstream.
Our previous larger, used, Airstreams each came with nice full length mirrors so it was a gotta have item when we bought our first brand new unit. After getting a very pricy quote on having a glass company install one we bought a very nice beveled edge full length mirror at Home Depot & attached it to the bathroom door, same as where the mirrors were in our previous units. We used mirror mastic (lots of it) and it works like a charm.
We also have a smaller vintage Airstream mirror, from a 30 year old unit, that we hung using copious strips of double sided tape and mirror hooks (yes, we had to drill into the interior wall to hang the antique mirror 😣
. Anyway, that mirror hung there for 27 years without problem and is now in our new unit, attached same way. If you decide to use screws in addition to mastic or tape just be sure the screws are not so long that they come through the other side.