We were looking at older Airstreams also, until we went into one and it actually felt too closed in for us. We imagined it raining outside and trying to fit our 2 grown sons and us in it comfortably and changed our mind. I then started researching Avions and went into one and was surprised be the amount of room it has. So we now have a 1978 Avion 30'. The cabnitry and flooring are built very well, and with a rear bathroom there is plenty of room to move around. Ours has 2 twin beds and a sofa bed that we plan on replacing with a dual reclining sofa soon.
So I would suggest spending some time in a few different types before jumping in with both feet.
I had the hooks placed all over my last trailer for hats, keys, jackets, ect...with no problem. But then I put a few of these: Command Large Caddy in the trailer and they lifted/seperated the wallpaper from the wall. I carefully removed them and the paper stuck itself back to the wall with no sign it had ever seperated. I think these were just too heavy. But I do have several tin signs and a clock hanging with the command picture hanging stuff (like plastic velcro) and have never had a problem with those.
I was selling a 18' trailer earlier this year and wanted to get it cleaned up, without having to bring it home from the storage lot. I got a quote of $10 per foot, then he proceded to add it up 18'x2=36', then added the width of 8'x2=16', 36'+16"=52', so $520! I told him NO THANKS!