Are we talking about cross country towing, or a 15 minute trip across town to the boat ramp?
If local, and the ramp conditions aren't too bad, I'd go for it. A steep ramp, a wet ramp covered with sand, a shallow ramp that requires you to back into the water, etc, and you may want to invite a buddy with a 4x4 to go along - just in case?
Note that as the boat is rolling off the trailer, there is a point where it's weight is actually trying to lift the back of the truck up. If conditions aren't just right, that could leave you in a world of hurt.
Agree with above, and some more comments...
OP, what model year, what axle ratio (needed to find the right towing capacity) most data I've looked at show around 8000 for trailer, combined weight around 14000.
If you do not upgrade to a 4x4 rig, then at least install a front mount receiver and wiring for a portable winch, say around 3500Lb capacity, if stuck on the ramp, you'll need a good Samaritan to let you use their vehicle as a winch anchor.
I pull a 20 foot cuddy cabin with a Ford Ranger and occasionally need 4-wheel drive to come back up ramps.
My I/O and engine are out past the trailer axle, so not much tongue weight to provide traction on steeper ramps.
As for highway driving, I tend to turn off the automatic overdrive feature, and plan ahead for uphill sections.
Good luck, see you on the water.