This thread reminds me why I transferred my macerator pump from boat duty (which it never was used for) to trailer duty. I don't have the high lift axle
and no tank available at the time was low enough to drain from the trailer into a tote. Inserting the macerator pump at the outlet allowed me to pump black water "uphill" into the tote.
While I may be "full of it" I rarely stay long enough in one spot to need to drain the black tank in mid-visit.
I've also used it to speed up draining of the grey tank and once to get the grey water up over a berm around a dump hole at a private campground. It was a weird arrangement.
To power the pump I put a Marinco 12v outlet back by the shore power outlet.
But back to the topic which is having to deal with a low sewer outlet...
I have two totes, only one of which I pack on any given trip. A wheeled one (~15 gallons) and a 5 gallon tote I use to "decant" off some grey water (when I feel guilty about snaking a hose off into the woods). In those cases I just use a hand bilge pump to get the water up into the 5 gallon tank. Plumbed it with some lightweight bilge hose and one of those 3" termination caps with the hose fitting and the pump mounted to a short piece of 1/2" plywood so I can step/kneel on something dry while keeping the pump from skating around while I'm pumping.
It's another device I had for the boat and repurposed to the trailer. The hand pump won't deal with the chunky bits, if you will, of waste water, but will do perfectly fine for grey water.