Yes, in the top photo, the fresh water tank is on the left. Would 35 gallons be enough fresh water. Guess that depends on what you're using the bus for.
My bus is for sale!
I have a round 125 gallon vegtable oil tank in one bay and a 55 gallon round poly tank next to it for gray water. In the next bay is a 75 gallon round poly for fresh water. Next to it is the elongated black tank. I like your two square tanks. The system you built looks well though out.
For a quick fix I am going to go with round poly that I have. I am shooting for retirement in 4.4 years. Yes 4.4 and some days to be exact. It will take us a year to finish the barndominium. Then I plan on breaking the bus down and refabricating some things. I will probably use your ideas there as a model.