Propane might survive a wildfire if it is in a well cleared area, and preferably buried. The Paradise, CA fire had lots of reports of propane tanks exploding. (The state now requires 10' clearance to dirt around the tanks)
Defensible Space | CAL FIRE
Our county wants 20'.
Yes, I wouldn't want to try to get a permit for 1,000 gallon buried underground storage tank, especially as I know that there is a volume cutoff (55gallons underground) that gets you into larger regulations. I know that there is some exemption for farms and ranches, but I don't recall the limits.
osfm.fire.ca.gov
I think your point on oil fuel is well taken. #2 heating oil and diesel may or may not be similar depending on the locale, but #2 heating oil is almost certainly short of lubricity enhancers and other additives diesel engines benefit from.
All the best,
Peter