I'd go with the low pressure as much as possible, since you need low pressure for your valves and your pilots.
Furnaces run pretty high BTUs so I imagine you'll have plenty of flow for a LP burner. It would seem to simplify the whole system to have low pressure burners, pilots and valves, and just regulate the tank down to that pressure at the source.
"People should not be afraid of their governments. Governments should be afraid of their people." - V
Secondary: Shady Lord RIS, Water to Barleywine, Pumpkin wine, burnt mead
Kegged: Crappy infected mild
Bottles: Apfelwein, 999 Barleywine, Oatmeal Stout, Robust Porter, Robust smoked porter, Simcoe Smash