Making him part of a state's "Fish and wildlife" would give him statewide authority, although the limits vary greatly from state to state. Some states have them pretty much hogtied in what they can't doe, others not so much.
In pennsylvania, for example, there was a major stink a few years ago when it came out that Fish and Game regulations gave them (or so they thought) a ridiculous amount of extralegal power. Agents were conducting midnight, warrentless searches with no probable cause, random and arbitrary confiscation of goods and property, "indefinately detaining possible witnesses by locking them in cars in august with the windows rolled up", shooting people's dogs because "it looked like it might possibly be a wolf hybrid" without actually proving the animal was a hybrid.
By the PA legal code they actually were granted, or, more accurately, not prohitted from thos actions due to sloppy, sloppy wording. Meanwhile, representatives of the agency actually claimed that they were exempt from not just the State but also the Federal Constitution because neither referred directly to that agency specifically. (Let's just say there have been some reforms in recent years.)
Point being, in a statewide agency, you could invent a lot of wiggle room for jurisdiction and authority for him if he's in a state wildlife, environmental, or "land management" agency. You can splash around an awful lot of grey paint without hitting the sides if you go that route, particularly if it's a slapped together, "interagency task force".
Don't forget that indian reservations will fall under the Federal government's jurisdiction. BLM and FBI. Florida also has a goodly number of old military installations and training ranges which while abandoned, are still DoD property.
