Rather than band-aid the pump with a cooling shroud, try to determine the actual heat sources and eliminate them.
The problem can be broken down into two categories, (1) heating the fuel before it reaches the pump, and (2) heating the pump itself.
The RVs with fuel routed up the cabin centerline can transfer heat to the fuel through the floor; the source is engine cooling air outflow, and exhaust flow. Measure the floor and tunnel temperature. Insulate the belly skin externally
if desired. Add tailpipe length or point it/them downward.
RVs with a bunch of firewall forward fuel plumbing upstream of the pump pick up heat from the engine compartment air. Components like filter bodies, gascolators, and fuel flow devices make it worse. Relocate the extra parts to a cool area. Perfect is a short, insulated line from the firewall bulkhead fitting to the pump, and nothing else.
Can't do much about engine block heating of the pump, but I suspect a few measurements would find that block heat isn't a big contributor. The overlooked wildcard is radiant heating from the exhaust tubes
. It's not unusual to see a pair of pipes near or under the bottom of the pump. Think about it. The only parts of the pump which can significantly heat fuel are the inlet chamber and the valve disk. Both are at the bottom of the pump, and isolated from the engine block by rubber diaphragms. The thermal conductivity of rubber is more than a 1000x less than aluminum. So if there is no efficient conductive heat transfer path from the 200F engine block, might we consider the 600~800F tailpipes shining on the bottom
of the pump...you know, where the fuel is located?