A piece of 4" exhaust pipe tubing might be about right for the sump. If you want lighter, a section of an aluminum fire extinguisher bottle. The sump need not be directly below the engine if room is lacking. If the sump were offset to the side it might include the dipstick tube as well as the temp sender and drain plug/valve.

 

Here is one representation of the remote oil sump idea. In this case I would do dash 12 fittings at both ends and use the fire extinguisher bottle as the sump. A 2 1/2" flex hose from the flat plate on the bottom of the engine to the sump. A short length of tube, flattened on the sides to clear the bolts for the pickup and TIGed onto the plate and a dash 12 90 for the upper end and a bell shape formed into the end of a dash 12 90 at the bottom of the sump.

 

Or, a 2"X 2" aluminum channel across the flat plate with holes through the plate into the channel to drain oil. The one end blanked off. The the other end welded to a length of tube.

 

The entire bottom of the engine would be clear below 2".

 

Lots of ways to go here.

 

Lynn E. Hanover