Boy you asked for opinions, you got them.
On our 9th class A coach. A class A has more fluid capacity than a class C, better driving visibility. The dingy towable, you need to have one, it just makes mobility easier.
The 5th wheel as suggested sound great for better sleeping capacity but for long runs it would be tough with all kids in the tow unit.
LASTLY I BELIEVE YOU NEED TO RENT A UNIT SIMILAR TO WHAT YOU AND YOUR WIFE THINK YOU MAY WANT. I have been an RVer all my life but it is not for everyone.
I wish you good luck.