Locating a regulator outside the tank cover?

I have a 15 kw generator that will be run on propane. 500 gallon tank that currently runs the furnace only. There is a 1st stage red regulator under the hinged tank cover, and copper line to the 2nd stage green regulator at the house wall.

My plan is a separate system for the generator, and I already have an integral two-stage (Marshall 1232-BBF) that will feed 60-70 ft of 1" poly line with the appropriate transition risers at each end.

But it will be very crowded under that hat with the addition of this regulator and a 2-port POL manifold... and some kind of 1" pipe exiting to the riser too. I think it will all fit in there although it'd be a real pretzel.

The instructions for the regulator say it needs to go either under the tank cover or provided with a separate cover. If I mount the regulator on the end of the riser and run a 1/4" pigtail up to the manifold, what should I use for a protective cover?