I've been running such a system for over 61,000 miles on this Bus and 70,000 miles on the last Allegro Bus without a leak or any other problems. Given this a few comments. On my setups, moving the regulator placed it off the support piece that is welded to the LP tank. This was no problem except that when the plastic cover was re-installed the bottom was wide open. Since my LP tank is right behind the passenger front tire I was concerned that mud or ice could be thrown up into the regulator area and potentially clog the vent screen on the regulator. To prevent this I added a piece of steel (a 4" square electric box cover) to prevent this from happening.
On the extended stay piece, some issues. Since my RV has 3 LP heaters I found the extended stay piece you can buy off the shelf did not work. This was because when my heaters were on together the gas flow required caused flow limiters in the piece to set and effectively cut off gas flow and all heat. To keep them from shutting down I used a brass T and brass shutoff valves instead. This means I have to shut off the main tank and then open the valve on my aux gas bottle IN THAT ORDER when I switch over to my aux gas source. In addition if you intend to use the Acme plastic hand connection to the aux gas source and have a high flow, that flow limiter will also set. I drilled that out on my Acme fitting. Finally, some 20# gas bottles with the OPD valves have flow limiters built into that tank valve. According to Manchester Tank engineers, there are tanks and OPD valves that do not have this flow limiter built in. These limiters were a serendipitous result of the valve design and not required by any law or rule. I have found 3 tanks that do not have this feature and they work fine for my rig.
If I can give you any further info, please ask.
2013 Tiffin Allegro Bus 43QGP
2011 Chevy Silverado 1500 Toad