GB,
I don't think that there will be much of a difference in the physical weight between a class one or three hitch, I suspect that a 300 pound chair may be over the tongue weight limit for a class one.
This link limits a class II and class III at 350 lbs tongue weight. Personally I would go with the class III. I like the 2" reciever rather than the 1 1/4" reciever.
Hitches, Receiver Hitches; Hitches Online
I am guessing that he didn't mean actually TOW the chair, but rather to put it onto a rear carrier. I suspect as mentioned above that he'll need to add additional rear support for the vehicle to ride evenly.
Another option may be to pull out (at least) the rear seat, and ride it up inside the vehicle on ramps. Then additional support may not be needed for the rear suspension.
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BroncoJoe19
2006 Alt Fuel Jeep (electric)
'98 windstar 3.8L
'99 Crown Vic 4.6L
'90 Full Size Bronco 5.0L
I'm not a professional mechanic, take my suggestions with a grain of salt, or a cup of coffee
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