We stayed at Lake Navarino Forest Resort last weekend. It has excellent facilities including toilets, showers, running water, huge campsitses and power as well. cost us $30 a night. Probably best camping facilities I've seen.You can also do lakeside camping with no facilities and thats pretty cheap. I think bout $8 per person. Dunno bout the marron. I was at the dam bout sunset and didn't see any so didn't try but I'm sure there are some good spots there if you look around. Water is a bit muddy as there is all day water skiing and power boating there. Nice place though.

In the Boranup Forrest always does the trick for me down south especially on peak periods like the aus day weekend. Fairly secluded and only reachable by an easy 4x4 track, most of the crowds hit conto's. Kid friendly camp site (always a few running around playing spotlight at night) and some sweet beaches nearby. No marron nearby that I know of, unless you plan on jumping a few farmer's fences!