We have put over 35,000 miles on the trailer on our C-Dory, often staying in campgrounds or RV parks. I haven't come up with a fool-proof way to empty the poop tank... we try to get the boat in the water often enough that a full tank isn't an issue. When it has been an issue, we simply hold an RV sewer hose over the macerater outlet on the side of the boat and pump the waste into an RV sewer dump. Not as elegant as when using our RV, because there is no way to flush that hose with gray water afterwards. That means you will be using a hose to flush the RV sewer hose... and then you need a place to store both of those items.
You cannot use your shower or sink, unless you have some way to capture the water - most RV parks would toss you out if you dump any gray water on the ground. We use a dishpan in our sink and dump that in the RV sewer dump; we use the campground facilities to shower.
As far as heat and a/c: we use an electric heater on the boat when we have a plug-in and that works just fine. We do not have marine a/c on our boat, but we do use a small room-type a/c when necessary, through the front window... looks kinda Beverly Hillbillies, but it works.
On rare occasions, we have been turned away from an RV park... generally because they have had a bad experience with a boater dumping gray water, or because they simply don't know what to do with them. When we pull in to an RV park, I let them know we are self-contained and will be plugging into their 30 amp and not hooking up to water. Most of the time it is no issue.
As far as comments from other RVers, we have had plenty of questions. Only one guy who wasn't sure we should be there... he walked all around us and finally came up and said, "That doesn't look like any RV I've ever seen before. You sure you're in the right place?"
I said, "Well, we are the only RV here with radar. Plus, we're the only one that can go into the water more than once."
We let folks know that we have all the same amenities they have in their RV, just a little different arrangement. Not really an issue.
Best wishes,
Jim B.