Failed to consider the size of the Portable Dump tank..

Send it back. When you have to move the trailer at least 3 times to dump mid-trip and wish you had hassled bringing that tank for those 3 times.... then purchase it.

I was glad to be rid of my portable tank when I sold my pop-up. I have no trouble hitching up to go dump as needed. But frankly if you use the camp facilities a bit and some water conservation you may make a whole week between dumps. That is what we do.

Don't get all burdened with 'just in case'. It is a slippery slope.