Matt- I would suggest calling Tom at JMP and I'm sure he would be able to help you on any preflight info you might need.
For the record the plane that was lost at Superman was a Hustler. I've seen Tom operate his from as little as 250' of grass runway( take-off and land) with out any stress or strain.
I've only seen the Firebird fly off of pavement and it used about 200' for take-off and about 350-400' landing to a stop.
It sounds like some other people have flown their's off of grass. Don't know why it wouldn't work as it is the same landing gear as the Hustler.
Both are great aircraft.

Marty O