I agree. I'm late to this thread and it's probably all been resolved by now BUT since this is just visual advertising and all the OP needs is a painted cylinder shape the first step to me would be creating a lighter model.

Why risk denting your hood, or adding that much weight? Plus I'm sure painted it might look fine, but as a steel drum it looks too much like a ships smoke stack.

Lighter I think would add to ease of installation, removal and lessen the risk of damage. As it is, it looks like a huge scratch or dent just waiting to happen. The Honda Fit is a light vehicle. The roof is pretty much designed to stop rain and bird droppings...but my guess is there is more metal in the 55 gallon drum then the entire roof of The Fit. Not considering the inner body structure.

I wish you well with your business and I hope it ultimately worked out okay. Speaking as someone living in The Northwest, where we literally have a Starbucks every twenty feet. We need more coffee places.