to FRF and CONGRATS on your new rig!
Emptying the tanks are no major. Make sure they are full and empty from dirtiest to cleanest. Black first, galley grey second, shower grey last. The black tank is going to have the largest diameter PVC pipe with the largest handle. The grey tanks have the smaller diameter PVC and smaller handles. If you have 2 seperate grey tanks (some don't) eyeball where the pipes are coming from in relation to where the galley and shower are located to get the dump in the correct order.
I can't help with any places in your area but I'm sure some other folks around here can.