I would love to do this but the cost of the site is $200 to $300+, and the RV the same.
WHOA, Whoa, whoa. Let's pump the brakes here, pull over to the side of the road, and rest for a moment.
Sure, some sites can cost $300+ (Premium Meadow sites at Xmas with tax).
But are you going at Christmas? If so, the DVC cabin (rented like a hotel room not on points) is almost $750 (without the 12.5% tax added yet). (those are 2025 rates as 2026 Xmas rates have not been released yet).
But you don't have to rent the max expensive campsite. You can get a plain Premium (less cost) or a Full/Preferred campsite (Preferred less than Premium and Full less than Preferred).
Depending on rental trailer provider, they ALSO priced based on seasonal demand and size/luxe. And trailer rentals (whatever size you want) costs MORE (on a per night basis) on a shorter rental than they do on a week-long rental. So there are a LOT of sliding variables that you have to get SPECIFIC numbers for and not just be dragged around by generalizations.
A couple rules of thumb are that if you plan to be in the parks (or in other words gone from your home resort) every day, don't stay in a cabin or a campsite/rental. Stay at a resort room on site. But if you have kids and will spend a couple half- or full-days at the resort, then stay at Fort Wilderness which is great for kids - so much for them to do and explore.
I have a camper but am renting one next spring (bigger than what I have) to accommodate a multi-family stay but we spend 2-3 days out of 7 in the parks and when not in the parks we are outside enjoying the wide open spaces, camper vibe, and walking around looking at setups and talking with strangers (campers are very nice and chatty).
Of course there can be extenuating circumstances and details so everyone's case may be different from the others of us.
I'd do a cabin, hands down. A real bathroom has a lot of value to me!
I get this. I do. But the camper bathrooms are not much of a step down. The Fort Comfort Stations (showers and bathroom facilities) are literally the nicest I have ever encountered in a campground and some of our guests use the CS when our trailer facilities are .... ahem .... "occupied".
In summary, a cabin is the most EXPENSIVE way to stay at the Fort and if a "real" bathroom is of the highest priority, then it's an easy choice. But for the cost difference and the difference in the resort experience, the rental route is a great option and you can take the cost savings and plow those $$$ into other experiences, memories, or merch that you wouldn't have done otherwise. And like I said, depending on how you run your park days, even ANY stay at the Fort is not the best fit.
Bama Ed
PS - some folks appreciate the cabin or trailer rental route to be able to eat when/how/what they want. I've read other folks say, "I'm on vacation and I DON'T WANT to cook on vacation". Okay, you're free to do that if it's your most important factor. To me, the food cost savings is plowed back into more nights at WDW the way we like to tour it. But .... whatever ....

There is no one-size-fits-all.