Catching up reading and responding.
First, ignore the anti-Thor trolls...
Second, dealers usually pay ~$20k less than Private Party
Third, I'd also recommend offering $65k but pay no more than $70k
Forth, I absolutely agree with a previews poster who said "what feels a little small, but acceptable at first, will feel tiny and unbearable after you've had it for a while" and other issues.
Finally, many places we like to go have sites for 30' but have 6'+ overhang past the curb (back in), which is why we looked for RVs as close to 35' as possible (ours is 34' 7"). The key is to try to research in person or through some reviews, which can you can fit in. We respond we are 30' if asked, because we know we fit before we go.
Good luck and great adventures with your family!