Whatever tank you decide, from 55 gal food-grade barrel to semi-permanently mounted tank, I'd second the 12V pump. I picked up a 12V boat bilge pump for $25 from a Boat N RV store near me (I know, we don't buy full units there, but they've got a heck of a parts dept,) and hooked up a section of water or garden hose to the outlet. Then you can just drop it in the tank with its wiring harness plugged in to your truck or TT, turn it on and pump 'er out. Good luck!
2015 XLR Hyperlite 30HFS5 (mods being performed regularly)
2009 Salem LA 292fkds (gone)
Nights- ('12)23 ('13)23 ('14)15 ('15)31 ('16)25
2014 Harley Davidson FLHX (XLR cargo)
2014 VW Jetta TDI (diesel sipper, camping support vehicle)
2011 Ram 2500 CC 4X4 CTD, B&W Companion (toy hauler hauler)