Appreciate the replies, everyone.
I had never considered a flail mower mainly due to the maintenace liabilities behind them, but leonz does make a good point in that they'd be able to dispatch a lot of the clipping and debris once cut. The plan with all this tall grass is to get it mowed and then drag the field to disperse some of the junk and help it break down.
As for everything else, I'm fairly certain there are no hidden obstacles hidden below the grass. I've walked the property numerous times trying to get a feel for it. The area is not very rocky, but ant hills and gopher holes could be present. No debris, the previous owners seemed to designate the woods along the edge of the property as their dumping ground....washers, ovens, metal sheathing, you name it.
I think I'm going to go ahead with the finish mower and cut it at 4" this time around. Take it slow and steady around the real high patches. In subsequent mowings as growth begins to start up in spring I'll gradually work it down to a 2-3" cut. If I get out there and it seems to be too much I can always borrow a brush mower from a friend. It would be an inconvenience, but it is an option.