Eroding rubber hoses in the power sterring system

I just talked to Monaco about the eroding hydraulic lines coming from the hydraulic fluid tank in the engine compartment of our Monaco Dynasty and Rob in technical support tells me they are not pressurized at this point. I can either have someone make up the connections and hoses or mend it inline with a fitting and clamps. He estimates about 5 gallons of fluid could drain out. (doesn't look nearly that large to me) and he said we should replace the fluid since it's never be changed since 1998. Either using AW 46 hydraulic fluid or automatic transmission fluid. I think the fluid is cheaper. It's important to not have that hose blow since it powers the power steering and other functions. He had no idea of the size of the lines.