Without running back to see... that sounds like me.
I hate the construction of most of these things. In a travel trailer, if she rolls over... you're going to have a frame left... not what you'd want in the passenger vehicle. I have wondered how they got away and still get away with the minimal though to safety approach.
Look at the school bus panel above the windshield and the stiffening rib running down the side... this one still has
some school bus DNA. Look at school bus crash pictures... and school busses are tough.
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This one has lost all traces of school bus construction and I think is mostly fiberglass panels... but I believe was still framed out in metal and would have fair structural integrity in a crash or hold up over time and miles. A monster truck show may gut the old "stick built" ones they like to drive through... but I doubt they have to weaken the structure more than interior removal.
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I don't outright hate or dismiss this era, and any bus that puts the driver in front of the tires is going to be an ugly wreck...
The true bus chassis, like in the Marathon Coach info, will always be overbuilt when compared to a purpose built RV chassis. Newell might be an exception, but I know very little about them other than they built high quality, high priced, "one off" types... way beyond my budget.
Fun trivia, the door I used on my build was originally from a custom job that was commissioned by Rusty Wallace. The outfit that started the build did so much, so badly that the next shop pretty much started over. My buddy worked in the second shop and I got that door and a bunch of bay doors for a song.
Slide outs wouldn't be a good idea on a million mile coach, but nobody seems to use them that hard... or at least not the original purchaser's.