Jac5n,
The concern I have with a plastic drum stored inside a building is a fire. If a fire occurs in the area, and the heat melts the plastic, you will have a sudden release of fuel that will increase the fire significantly. The dumping of 15-55 gallon of diesel fuel produces a lot of BTU’s of heat real quick. If the drum is in a low cost, do not care if I loose it type of building ( I wonder how many of us have building that falls into this category), then that may be OK. If you use a metal drum inside of a building, make sure it has a UL listed drum vent which will release the pressure built up and release the vapors and pressure without it flashing back into the drum. A tight drum and no way to release the pressure will cause a sudden release of the drum bottom and sides in a great BIG BOOM!
Just another thing to consider with a tractor!
Be safe.
Tom