So we're talking about a 1 inch drop in pressure in the volume of whatever amount of piping is in your RV over the span of 1 hour. That is not very much gas. run the same test again and after you get it to 7 inches WC, use the stove burner to bleed off enough gas to get it down to 6 inches. Then you can see how much gas is escaping in the span of that hour.
It could be leaking out through the burner valves of the stove, the electrical gas valves on the furnace, water heater, and refrigerator as well as through any fittings. You should also check the lines under you RV to see if there are any spots where there is corrosion or abrasion.