Slide out on 2005 Classic 30'
The key is if the stabilizer jacks are used properly, you will never have to look at the gap around the edges of the slide. The technique I use with my electric jacks are to extend them down one at a time. When you notice the body starting to rise at that jack, stop and lower that jack. As the pressure is released the body stops lowering. At that point you are providing the right amount of support to the frame, while not exerting enough to torque the frame and effect the slide.
While I never have had to do this, the slide can be opened or closed manually. I'll have to get out my owners manual and make sure I have the tools to do that.
'04 Classic 30' S.O.,'03 GMC Savana 2500,'14 Honda CTX 700