Older Diesel or New Gas - Newbie question

Let me preface this by I've read the faqs on gas vs. diesel and have been doing a bit of research. I know diesels will ride smoother, quieter, pull better, and go longer between maintenance intervals than gas (though maintenance will be more expensive)

THAT SAID, here's the thing:

We're full-timing with 5 kids and this will be our first RV.
option 1 is buy a 2004-2005 DP or
option 2 buy a 2016 Gas (Georgetown 364TS is what we really like.)

We need to tow a minivan behind us (the van weighs 4000lbs), and we plan on being in one place for 2weeks to a month typically. (are we parkers or drivers)?

I like the older Diesel option, but I'm afraid of what can be wrong that we won't know about until we own it. We're looking at a 2004 monaco for example, and we love it, but i know the tires have flat spots from parking, and the ac is being repaired and there was a small window water leak at one point. That's just plain scary.

Going new, at least we'll have Forest River behind the coach and have some piece of mind.

Would love some thoughts on this. There are a lot of older DPs in the $75-85k. It's tempting, but buying a used 10 or so year old RV scares us!