New does not mean better, sometimes it means worse. If you find a used vehicle get it inspected before, once you buy one take it to a mechanic that you trust and ask him to check it out and repair or replace what he thinks needs to be done. Then do this once a year or more often to make sure nothing is going wrong. On the road it can be hard to find a good mechanic, ask relatives if you are in their area.
As for the unit my choices for what you want to do would be A,C or B for the simple fact that you can drive, stop, eat, use the washroom, sleep and hit the road again without going outside. Not that you will want to do this all the time but there can be times that this is nice.
Are you crazy, sorry I don;t think there is anyone on this forum that could answer that, after all we are all on this forum :B :S :h