i know nothing of WVO conversion but I'm interested.

i found this page discussing vegatherm and fuel heating in general.

Electric (vegtherm or other) versus coolant heat FPHE : 2 Tank veggie oil conversion and General discussion

It seems to me you could fabricate a very effective heater with some brake line coiled up inside a 3" peice of pipe.

Advance Autoparts sells PolyArmor brake lines, they bend easy and are very hard to kink.

Is there any problem using coolant to heat the WVO to 190 F?

I'm very thick skinned if anyone needs to stomp on my suggestion

Dave