How nice to have a fiberglass trailer just pop up when you need it, especially in Florida (they're seemingly not as common on the east coast).
The former owner says that there was a leak around the vent that she fixed with some kind of magic RV tape.
I don't want to "rain" on your new trailer, but I would start by being skeptical of that repair. There is no "magic" RV tape that I know of that I would seal a vent with on a permanent (well, multi-year) basis. I get a hint of "quick fix." You may want to remove the vent and seal under the flange with something like butyl tape (this is a butyl putty that comes on a roll, not really tape).
If it was butyl tape that the previous owner used, but she just put it on the top of the flange, or around the edges, I still wouldn't consider that a proper fix. If there is a flange around the base of the vent (there usually is), then the vent should come out and sealant should be put under the flange. That's where it should actually be.
As far as brakes
go, I don't know if they were added to every Light
House trailer, but just know that a 7-pin connector is often used when there are not brakes
. In that case, it's often used as a way for an extra wire so that the tow vehicle can charge the trailer battery
Of course it can also mean there are
electric brakes. I think you can just have a look under the trailer to check. If there are electric brakes you should see them, and wires, leading to the back side of the wheels. Then you would need a brake controller in your tow vehicle in order to make use of them.