My next homebuild project is a LWB - something along the lines of a Tour Easy. Would like to follow that with a SWB, and recently been looking at the P-38. The pylon frame is particularly interesting, and can be clearly seen in your pics.
My penchant is for straight chain lines - no deflection or idlers. Not sure if possible on a SWB - looks very tight under the seat - will cross that bridge when I come to it I guess