Look for the hitch mounted model that swings away or down like the example in Crewzin's post. Otherwise the hatch is inaccessible with the bike rack mounted. Also match the receiver size of 1 1/4 or 2 inch. The 1 1/4 seems to be the more popular option for the PT.
Also, etrailer.com has a bunch of hitches:
http://www.etrailer.com/products.asp...rysler&t1=&h=e
and foldable racks:
http://www.etrailer.com/mm5/merchant...y_Cod e=BR114
I just ordered a hitch from them for my wife's Altima. Great service and prices too!