Larry is correct. Since your in Florida where it rarely drops below freezing you'll be fine with running an external cooler. One of the main reasons auto manufacturers use an oil to water cooler on the tranny is so the transmission can reach operating temp faster in cold climates.

Their is another option however. You can take your old lines to a hydraulic hose repair shop and they will rebuild them while you wait. Shouldn't cost more than $50 for the set. I have this done all the time and the replacement is always better than stock.
Adam

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Current Stable:
01 ML55 AMG
92 500E (a few mods)
87 300E (lots of mods)
00 Chevy 3500HD Diesel Box Truck
68 18' Donzi Marine
06 GT i-Drive7 1.0 Mountain Bike (with GPS!)

PREVIOUSLY OWNED:83 300SD, 87 420SEL, 88 420SEL, 90 420SEL, 86 560SEL, 86 190E 2.3-16V AMG, 94 E320