I like getting a good night's sleep. We have tried truck stops, Walmarts, etc, and seem to be a magnet for a noisy truck with a reefer pulling up next to us... can't take the noise!
As far as water coming out of your vehicle's a/c, that is expected. Water coming out of a conveyance used as an RV isn't expected, and will be grounds for getting you booted out. Not to mention that you will make it impossible for the next person wanting to stay there with a boat. The easy and real common sense solution is: don't do it.
While we're on the subject of Walmarts, check out this "Code of Conduct" endorsed by all the major RV groups, whose members may use a Walmart from time to time...
http://www.walmartlocator.com/overnight ... etiquette/
Staying at a Walmart is not a "right," and there are plenty of them that don't allow it, or local laws don't allow it.
We have also stayed at a couple different Cabela's, after asking permission. Yes, using the same etiquette as above. Casinos often have RV/bus/truck parking where you can overnight (some have full service RV parks, as well).
Our first choice is to be somewhere off the road, preferably with hook-ups, and quiet. In an RV park, you can unhook, leave the boat, and go out for supper if you like - that is another no-no in parking lots. You can take advantage of discounts at RV parks by belonging to Escapees, Good Sam, Passport America, and others. A Lifetime Good Sam card will also get you fuel discounts at Flying J and Pilot, as well as purchases at Camping World. You will also find many small towns that have a city park or fairgrounds with overnight RV parking.
I hear the term "boaterhoming" here a lot, but traveling on land with your boat is more like having a hard-sided tent while camping. Certainly better than sleeping on a pad on the ground, but you have limited use of your water facilities on the boat. You aren't going to be able to shower on your boat, so it is nice to stay at an RV park that has shower facilities. A 30 amp plug in will allow you to run A/C, a microwave, or TV.
Wild Blue provided us with plenty of nights on land, with reasonably comfortable accommodations.
Enjoy the trip.