As far as I'm concerned, head systems are the stepchild of the boat building business, and my guess is Hunter is no exception in this field.
Since you have what you have for a system and don't want to redo the whole it.
1. Get the best hose you can find.
2. If at all possible try and rebuild the line so that it has as little standing waste in it.
3. Don't use nylon fittings, seacocks, y-valves if they'll be full of standing waste. The nylon (even Marelon) will absorb 7 to over 8% of it's weight in moisture in just a few months in standing waste.
Fair winds