Yes there are ways to extend/retract almost any slide manually. So far, for us, knock on wood, we haven't had to do so in the 11 years we've had a unit with a slide. I don't know the mechanism the 25.2 uses but wouldn't be surprised if it used the same Schwintek system (by Lippert) that our 24.1 uses:
For the slide on the 25.2 I don't see why you wouldn't be able to extend it just about anywhere (including Wal-mart parking lots). If someone complained you could easily show them that is the bed and it needs to be out for you to sleep (and if all you're doing is extending the slide and not doing other things like awning, chairs, etc. LOL I doubt many people would even notice especially since it pops out lengthwise and not widthwise like other slides).
I'm interested in why you like the 25.2 over the 24.1 (I can see a few reasons, the bathroom being a big one)? Since they both, to me at least, have a very similar intent...