I've done the following with my popup leaving a Tent Site needing to drop a black tank load:
Drive around looking for a Full/Preferred/Premium on the morning of your departure (2 minutes). You can always find ONE empy site that has a sewer hookup for about 10 minutes. I nod to my neighbors as I get descend from my TV and connect to the sewer hookup for a few minutes. Nod and wave goodbye when you mount your tow vehicle. Now that the deed is done, I pull out for home.
There. Easy shmeasy.
Oh so easy.
Bama Ed