I think people are misunderstanding your comment and thinking you mean dump it in the drain.
For those people, there are actual sewage dump stations at a lot of those places. Look for a sign with a vehicle with an arrow or pipe out the bottom next time you're near a truck stop or state park.
It seems like OP is already halfway to the RV lifestyle, and he's probably in close proximity to dump stations, so he might as well dispose of it in the 'correct' manner rather than throwing it in dumpsters meant for trash.
Unless his purpose is to pollute other peoples trash bins with human waste than it has no impact on what he is trying to do it is just a safer way to dispose of his waste.
For those people, there are actual sewage dump stations at a lot of those places. Look for a sign with a vehicle with an arrow or pipe out the bottom next time you're near a truck stop or state park.