Strictly personal opinion from someone who has just bought a brand spankin' new TT...to use it like you're thinking, I would certainly check out the CG first to see if there are any good used for sale. They're absolutely right on the depreciation and we took all that into account. We bought our ROO 23SS hybrid brand new and for us, it's worked out. But we're "old folks" and this new one is our last camper.
We visit various parks. We feel like that is part of the camping experience. Years ago we had a cottage on a lake and loved it, but it turned into a work-weekend no matter how hard we tried to avoid it. I think you might find this to be the case, whether you know it or not. Before I absolutely committed to a seasonal/semi-permanent site, I'd get the map out and see what is out there within 1 - 2 hours drive. In our case, we can visit probably 15 TN, MS or KY SPs or COE within 100 miles. Our very favorite CG and the one we love the most is 45 minutes driveway to site...minus the stop at McD for lunch on the way. Another concern - at least it would be for us - is that many of the parks that offer seasonals end up looking awfully junky. Folks haul a years worth of firewood, a boat that they leave, chairs that get blown around....not what we want in a campground. That is not to say that they're all the same, but I'd really check it out first. If you're absolutely sure this is the way you want to go, maybe look into a small-size park model. It would be sort of a combination TT/cottage. Not easy to move if you change your mind.
Hope you'll do some more homework before you sign on the dotted line.