Lipets,
I'm my own personal opinion, you're making a big mistake not even looking at the gas units, at least that is what I'm gathering from your posts. I had a 2005 Holiday Rambler Endeavor DP with a 400 ISL engine in it and air ride suspension and it did not ride that much better if at all than the F53 based Itasca Sunstar 36D we just got about a month ago. The 22.5 tires and the chassis technology on the gas units have come along way to give them almost the same ride as the bigger DP units. Also, my 22k chassis has 4600 CCC and can tow 5000lbs. That's some crazy numbers! A lot of DP do not even come close to the 4600 CCCs.
Being a diesel man(owned several GM trucks with the Duramax/Allison trannys) I wanted a DP and all the power that I could get. Well, this F53 surprised the heck out of me for its performance coupled with the Ford V10 and the Torq**** tranny. We have gone up the same NC mountains that we did with the truck/5th and the Endeavor and we lost very little as power was concerned and we could actually carry on a conversation with a normal tone with the wife even with the engine working hard at around 4500rpms while towing a Prius on a dolly which would come close to about 3800lbs behind us. Steepest grade so far has been 8 degrees for about 4 miles and we went up at about 50mphs. I think I could have gone faster but did not push the coach. Came down same mountain leaving it in auto and letting the Torq**** tranny do its work and it held my coach at 30mph with very little effort that I did not manually downshift. I just tapped my brakes at top of the grade a couple of times and the tranny took it to the right gear and away we went.
Anyway, my point is that you can get a fairly nice late model unit for the amount of money you're budgeting for and you do not have to worry about things breaking down in the near future. Mine is a 2011 and had 8600 miles on it and barely used and we got same rate as a new coach and got a 5 year bumper to bumper warranty for $2,600.00 because it was only 2-3 model years old. AN older unit would have cost at least double that. You get to the 8-10 years old range, things are bound to go wrong with the unit like fridge, air, ect ect and those are not cheap to fix. It's your money but I think you would do yourself an injustice if you did not at least drive a Winnebago or a Tiffin gas unit which are well made and have a huge amount of storage and CCC. Yes, those are the 2 I would look at as far as gas units. DPs are not what they are cracked up to be, IMHO, unless you get into the 500k plus units. Also, make sure that the state you live in does not require a different class drivers license to operate anything over 26k. NO, I'm not talking about a CDL but you could need a regular class A or B t operate something that heavy. I can run mine on a regular drivers license.