I have a similar one to that.Heater the type of heater I have in mind
I’ve used mine working on a tractor outside under a tarp.Lots of heat is fine. The wind will take it away quickly. I'm looking for something tough.

Huh? I'm not heating a cab.Both Webasto and Eberspacher (ESPAR) make gasoline and diesel fired cab heaters with thermostats, timers, etc. Why ****** around with MickeyMouse **** when there is a correct thing to SAFELY do the job properly>? Oh...you can get Chinese knockoffs (Vevor, etc.)
I prefer propane, no spills no smell. The liquid fuel heaters are also very picky after riding around in a service truck. But a lot of the new propane ones are also coming with too much safety BS per their online description. I don't need a faulty optical or heat sensor shutting off the fuel on a sub zero day, I'm more than capable of babysitting the unit a few feet from me.Assuming you have a power source on your truck (generator / inverter) there are tons of these "torpedo" heaters out there. The only question is what do you prefer for fuel? I like propane over diesel, and I'm not huffing burnt diesel exhaust while working. Means carrying a propane tank, but a BBQ tank will last about 2 shifts - enough to get a tank refilled if a job runs long.
I also packed a pop up that I'd rigged canvas tarp "curtains" to that attached with carabiners and ties to the legs, and a couple coleman lanterns; I could turn an outdoor space into a heated workshop if it got brutal. ALso became a mini command post during some emergency events, when everyone eventually got "Cab Cabin Fever"...
Huh? I'm not heating a cab.
I prefer propane, no spills no smell. The liquid fuel heaters are also very picky after riding around in a service truck. But a lot of the new propane ones are also coming with too much safety BS per their online description. I don't need a faulty optical or heat sensor shutting off the fuel on a sub zero day, I'm more than capable of babysitting the unit a few feet from me.