First, I'm glad you and the 'bird are ok. That is very repairable damage, although that doesn't make it any less frustrating!
Having had an oil fire in the engine compartment last year during the GG autocross, I can attest to the importance of having an extinguisher at quick disposable. So much so that after that event, I ordered a second one. I now have 2 inside of TOW, one behind each seat attached to the rollbar. I can't find a picture at the moment, but this is what I used to attach them.
Given how that mount works, I think it could be attached to about anything with the 2 holes in the base, although I use stainless bands to attach to the rollbar.
Also, I have a Halotron extinguisher. I do not remember the details at the moment, but the different extinguishers are designed to tackle different types of fires. As I recall, the Halotron is a clean agent that doesn't leave residue (ie: much easier cleanup) and is designed to target chemical fire moreso than a material on fire.
Point being... Don't just buy the cheapest product you can find, as some may not be good for the type of fire we are most likely to experience. This is a place that research can be time well spent!
Jay, keep us posted on what you find, although there may not be enough evidence left to get a good answer. Oil and gas fires are no joke!!! At the COTA event I attended earlier this year, there was a car that burned to the ground due to a gas fire. He pulled the extinguisher system as he got out, but a fuel like ruptured and just kept feeding it. Scary!