I skipped from page 6 to page 14, so pardon me if I missed something important.
That said, I am glad you are re-thinking your purchase. First, the lack of accessibility with slides in. Think of it this way: if the slide malfunctioned, would you be ok camping in it anyway? If not, pass on that model.
Second, the length issue. The longer the tail, the more leverage it has to wag the dog. Know what I mean? With a long enough and stout enough lever, you can lift that trailer all by yourself... maybe only a half inch, but you could do it. Ok, 30' is a pretty long lever and 35' even more so. You definitely would need a hitch with built-in sway control, but even with that you might feel uncomfortable when towing in strong winds or when big trucks pass by.
Third, you'll have a much harder time finding a campsite than you would with a 25' TT.
Fourth, the struggle your Burb will have with a big trailer. In that regard length is not the issue. The issues are #1 frontal area, and #2 weight. An 8' wide by 127" high TT is pushing 45% more air and wind than a 7' wide by 100" high TT.
DW and I started with a 23' Rockwood TT with 1 slide. Since then I've bought smaller trailers only. All of them around 16'-17'. Easy to maneuver, easy to fit into smaller sites and in tight CGs. I like national forest CGs, and some of them just can't accomodate anything over a certain size. I also like smallish tow vehicles, BTW. I've towed over 140,000 miles with my '08 Toyota Highlander. That's just my preference. For your family and vehicle, a 25'-26' TT should be just about right.
And if I may suggest it, please consider a used TT. That Rockwood I mentioned off-gassed for about a year after we bought it, freshly built from the mfr. This is not un-typical. The formaldehyde and chemicals used in the typical TT interiors will sting the eyes, nose and throat of many people. Buying a 1-4 year old, used TT lets you escape that break-in period (much healthier) and miss out on the worst part of the inevitable value depreciation. If you decide a year later to sell the trailer, you won't lose much money on the pre-owned one but you will lose thousands on the new one.
Oh, and make sure you know how heavy your trailer's tongue is when it's loaded for camping. Don't guess or presume, you may be shocked! Especially if the fresh water tank is up front, like it was on my Rockwood. Water weighs 8.3 lbs per gallon, and the trailers you are looking at have huge tanks!