I have the same Griffin itrip and it works sweet in the sticks. You find a station that nothing is being broadcast on, set the itrip and away you are on your magical tune-filled ride. I use the lowest FM station available (87.9 I think) and will occasionally get minor intereference from passing trucks. It plugs into the docking port of the iPod. I will second that it draws much more battery than usual, ~7-8 hours as opposed to 17+(found that out last week on our way to Rothbury and back).
I assume no tape player, because I would just go for the tape to iPod connector (we used a CD player one, worked just fine) and you can pick one up on the cheap.