You won't really be needing the tranny cooler for this weekend. It's not a real necessity for towing, as long as you tow under the capacity of the 1500#'s. For extending towing and continous towing, it's highly recommended as well as an external filter.
The real problem in getting a cooler is the location and size. On my -7, there is a big pusher fan up front as well as the thermo-clutch fan behind. The pusher fan is enacted to support the cooling as well as the A/C. It's quite tight up front to locate a tranny cooler.
I'd suggest that you first figure out a location and size preference to fit that location. Then start looking for a cooler that would work.
When looking, most automotive stores carry tranny coolers, but these are mostly standard commercial sizes. Other type of stores that may carry tranny coolers: towing/camping, Walmart/Kmart/etc, auto part stores, and don't forget to check Ebay.
The kind of cooler you would prefer is the continuous tube rolling back and forth. You could get the 'stacked' type, but it's not as efficient.
