You're not going to be able to heat the building (the way it is), no matter what you use. All you'll be able to do, is "heat yourself". If you use kerosene for an extended period, you'll start feeling ill due to the smell and the CO.

the heat loss alone of a room that size is nearly 100Kbtu, add in the total open construction, and the massive air infiltration and you are looking at nearly double that, factor in the height of the space and construction of it, and you are looking at a nice 360K salamander to get and keep it warm, a better way is to mount a radiant heater where you are going to be working in there, that heats just you and the stuff you are working on. much smaller need for heat.

If you just are usually in a certain part of the barn, can you box off part of it with some studs and drywall and some insulation? That way it would be much less of an area to heat!

If you are not going to fully insulate and eliminate infiltration, Infra red heaters are the best solution. They will not heat the building, but will heat people. They should be a suspended type and angled downward for best results. You can strategically locate several smaller units where you will be working. Checkout the 'Mr. Heater' web site. Use a model that vents to the outdoors to eliminate condensation problems.

Here is a link that might be useful: Mr. Heater

Thanks for the messages guys. Kind of bummed because I found a 210,000 btu salamander heater for 250 on e-bay. I was hoping I would be able to use to heat the barn occasionally. I like playing corn hole and wanted to play in the winter. Sounds like the salamander will smell too bad????