I've towed my SeaDoo boat, a twin pack of jetskis & a utility trailer carrying a Dingo (not all at the same time).
The only problem I have ever encountered is that time I couldn't stop in time when the trailer was empty. If you are going to tow on a regular basis, you may want to consider diabling your ABS.
Tom
Which SeaDoo boat have you hauled? I'm interested in getting a Challenger, which is their 18 footer...
Would there be any probs with towing that size?