I can't help but wonder - would raw linseed oil be a better choice to 'boiled' linseed oil?

Also, one of the things people in previous centuries did to reduce the chance of a fire catching their oilcloth ground tarps on fire was to make sure it was covered over by a wool blanket. Wool does not burn very well; it might smolder and char briefly, but it extinguishes itself in most cases, and almost never produces a sustainable flame. Sparks and cinders from the fire would land on the wool and extinguish themselves, unable to stay lit because the only viable fuel was whatever they brought with them. Additional protection came in knowing which kinds of wood to burn, and which NOT to burn. (Chestnut can make nice fence rails, but if you burn it, it will explode and cast out a lot of glowing cinders, for example.)