Wally,
I HIGHLY recommend you go for a larger hitch. One with a 2" receiver.
Why, sure you may not need it to pull the p15/trailer, but with a little
extra investment in your hitch, you can use a "hitch haul" (a metal grate
platform that goes into your receiver) for extra utility, or to haul your
greasy leaking motor *outside" your carpeted car when taking it to the
repair shop, or for hauling your spring manure bags home to your garden.
They even make one with a ball on the tail side of the hitch haul so you
get the storage *and* can tow your trailer. A receiver makes it easy also
to use the hitch for those special bike racks that insert into the hitch.
If you have a family and the family bikes, its a good way to go for hauling
your bikes..., Versatility in the hitch you get is a good thing.
The other thought is with your aerostar you can haul that Uhaul trailer to
move your brother in law on saturday, or a large trailer to bring home that
big new freezer refridgerator your wife wanted, etc.... without worring if
your bumper mounted cheesy hitch will come off. I think it makes sense to
get a 2" receiver hitch for a little extra money.