How much can it handle?

I have a 1994 Transport 3800 with 215,000 miles. Recently I have acquired a 19 foot fiberglass sailboat. I looked into getting a truck to haul it, and then selling the van, but a salesman at a dealership thought that if I took the money I was going to spend on a new truck, and instead put it into the Transport, that it would be a fine vehicle for towing. The boat isn't extremely heavy, but it certainly would add a large load to the Transport.
Is the salesman right? Could my transport haul the boat without causing major engine or transmission problems? Any help would be great.

The boat isn't extremely heavy, but it certainly would add a large load to the Transport. .
I think front wheel drive were not born to haul heavy loads. I'd do it ..and I've done it - but only occasionnally:
- no question to try to beat the speed limit
- no steep or long hills
- short treks only
- never NEVER use 4th (OD) position

Yes the transmission is at risk, and if the intention is to do that regularly, I'd think a bottom line 3rd hand small pickup might be less expensive than rebuilding a transmisson . But I have seen some haul heavy stuff, but was not told the result. In any case, an extra transmission oil cooler is the first item I'd think of.