I'm not a local, but I go down there enough to know the lay of the land...
There isn't a park, but you don't need one there. The resort's cat skiing operation is totally sweet, do it if you have the money. If not, make sure you hike Mary's Nipple at least once--its a quick and easy trek to great skiing and a view that is out of this world. There's an incredibly obvious and long cliff band next to/above the Sacajawea lift that you can go as big/little as you want off of. You can scope most of it from Middle Earth (look at a map). You can also rage as hard/soft as you want at the Royal Wolf bar in Driggs. Watch out for cops between Driggs and the resort, one almost always sits near the state line. Have fun dude, lets hope the snow gods are good to Targhee and the rest of us in the northern rockies next week!