120 L
is a lot of water compared to a 13' egg tank, and lot if you had to carry it, but with a flush toilet, shower, and running hot water for washing, it's easy to use a lot. The tank size is similar to that in
Bigfoot trailers of similar size, and tiny by big RV standards. It is a significant amount, and should certainly be enough for a day!
I assume that the tank layout is driven by the grey tank location, which in turn determined by the bathroom (specifically the shower). In my RG, the shower is across from the door, ahead of the
axle, so that's where the grey tank is; the fresh tank is thus just behind the
axle. In the SG, the shower is in a rear corner, so the grey tank is presumably rearward, and the fresh tank forward. Since underfloor area is entirely open other than the tanks and axle, and the RG tanks are about the same size as each other, I don't know why there would be a
size difference between RG and SG... but I've missed the logic of some other trailer design decisions.
I adjusted my fill hose position to help it fill better, aiming for a continuous drop (no accidental U-traps) and not letting it go above the fill port (as the broken remaining piece hose was when I bought it).
My flexible extension is a hose barb with female hose thread as an adapter, with a short piece of clear vinyl tubing hose-clamped to it. I have a hose-threaded elbow and shutoff valve between this extension and the hose end, so I can leave the faucet on and control filling with this extra valve. The elbow (a nice large radius bend) allows the hose to hang down without its
weight kinking the vinyl section. I later found essentially the same thing (although not clear and less flexible) as an inexpensive commercial product in the Canadian Tire RV section - I'm sure it wasn't there when I assembled mine, or at least that's what I tell myself!