Hey there, my 1960
18' Traveler, albeit not a Bambi, I am sure is similar. It came equiped with a 25 gal water tank, toilet and Kitchen sink as well as hook up for shore power and water. There was no 12V
water pump (it came with a bicycle pump and valve stem on the water tank fill for pressurizing the system and bowing out the lines
I added a 12V
system. The black water tank is only about 6 gal and the "grey water holding" was pretty much just what the pipes from the Kitchen sink to the black tank could hold. I replaced sections of the grey pipes with 4" to maximize grey holding and minimize the amount of space holding tanks take up. Have fun on your search!