The difference between a 24' and a 26' is negligible; however remember that actual bumper to bumper length is almost always more than the stated length of any RV. On either (24 or 26), you will have problems with overhang and tail swing compared to any car or large truck, especially if you are going off-road (even mild off-road). Yes, pnichols (above) does it, as do many of us; but I'd be willing to bet that he has significantly more experience driving an RV than Mountaintraveler does. Additionally, the house portion of a class C extends significantly out wider than the cab; something that takes getting used to for a newbie, and a 9'-11' height doesn't just come into play in camp sites, but also while driving on some small residential streets.
Removing a swivel chair and/or a jackknife sofa MAY provide room for the OP's cot/camp chair, but I'm really not sure of the point, and many jackknife sofas also have stuff under them (water tank or pump, water heater, etc.). Removing a dinette is much more challenging, and will likely render it useless (for future reinstallation).
Reading what the OP is planning makes me think that they want to do the same type of camping that they always have, i.e. boondock tent camping, and in the same locations, but with the amenities of a class C RV. Sadly, I don't think that is possible, and while I could be wrong, this kinda looks like a train wreck waiting to happen, particularly considering the OP's eyesight issues and admitted problems with parking a car. Realistically, buying a transit van and installing just a sink, stove, fridge, and porta-potti, leaving room for the OP's camp chair and cot, would be the best answer.
