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In used gassers and all coaches for that matter you will have to be concerned with the weight of the unit your looking at.
There are far too many coaches built on too light a chassis , and the problem is that they have a lot of space to carry all your passengers and gear, but don't have the capacity to handle the weight of what you can put in them.
The coach's CCC ( Cargo Carrying Capacity ) will be listed on a , weight sheet , somewhere in the coach; cupboard door , back of a closet; and will give you numbers for the weight you can safely carry and how it is calculated. The sheet will also list the tow weight rating of the unit, so you can calculate how big your towed vehicle can be.
For a coach in the 35' range look for a CCC of 3,000 lbs. or more , and a tow weight rating or at least 5,000 lbs. Anything larger than 35' should have more.
B-I-L, had a 35' gasser and had to chose between filling the gas tank and carrying water to flush the toilet to stay under the GVWR of his coach.
Weight sticker will look like the picture below.
99DSDP 3884, Freightliner, XC, CAT 3126B, 300 HP /ALLISON 3060
2000 Caravan toad, Remco & Blue Ox.