RE: advice on best rv for my family
I am like LEN, a TT would probably be the best. A couple of options, mutiple slide outs a must. The bigger you can make that trailer, the better. Bad weather days will be come rather cramped. TT can come with bunk beds. I have seen some models with (4) in the rear. I would also suggest looking at toy haulers. Most of them come with (4) fold down bunk beds in the toy section of the trailer. Either way, it is going to have to be long.
I noticed you mentioned allegeries and diesel? I have never heard of that problem before. But, you might want to re-visit the diesel. They burn considerably alot cleaner now and are much quiter. You will need a lot of ponies under the hood to pull what you are looking for.
I hope this helps.