Impressive (and ingenious) mods, but be careful !!!!!
Your trailer specs are:
Empty weight: 3245
Max Cargo: 1230
GVW: 4475
So far, you've indicated about 400 pounds of battery/battery box to the tongue, a Xantrex inverter system, larger steps, and now a pump/filter system for the gray tank and a significantly larger fresh water tank. It looks like you're close to approaching your GVW (without any camping gear in the trailer).
The Hideout 177LHS is a single axle 21' lightweight trailer. I'd urge you to not add too much more or you're going to be looking at things getting "rough to keep together" should you hit a bump on the way back to Glamis...
