The roadsters, both SRT6 and NA, have that extra bracing under the trunk.
I wouldn't think it would be too much effort to fab up a light hitch to pull a small trailer like the bikers do.
Then you could carry both a 19" and 18" spare with maybe some room left over for a few 6 packs on road trips that are beyond your AAA towing limit !

( this one looks pretty sweet 1 : http://theusatrailerstore.com/rally-...cycle-trailer/ )