I have used them and yes sunbelt has them. Try and locate a propane powered unit for that job. Not sure of total access in and out but with out seeing the area to enter it might be difficult to access. They usually have a dust containment all in one. It's a drive on unit. Not cheap to rent for a day either nor is the steel shot. I do however think you are in the right direction for that job.
Good luck Jim!
Good luck Jim!