I’m willing to give it a go.
I’ve got the excess solar from the rooftop solar panels, the electrical and electronic knowledge, and the gas fitter and metal fabrication experience.
I have an oil free air compressor, and anyone can by a helium based cryo-cooler. I have an account with an industrial gas supplier.
Just enough knowledge to be dangerous.
If Nile Red hasn’t blown his lab up by the time I publish this comment, I reckon I stand a chance.
Efficiency pumping your excess solar into the EV itself is more like 80-85%, most of which is loss in the electronics, not the battery - those typically have a coulombic efficiency of over 95%.
Hydrogen a boondoggle. It's not nearly as stupid as making ethanol from corn (which is an energy-negative process) but it's close.
Also, "gas fitter and metal fabrication" experience isn't worth anything unless it was hydrogen-specific. It is far leakier than natural gas/propane. One of the biggest hassles of a hydrogen fuel chain is that the stuff leaks through everything.