I am re-wiring the trailer. I need to decide which trailer connector
(4-, 5-, 6- or 7-pole) to use. The trailer has a surge brake that is
a disc brake. The minimum requirements for the new wiring are to do
these:
Left turn signal
Right turn signal
Running lights (marker and clearance)
Brake signal
Disengage the disc brake when the car is in reverse

Optionally I would like to be able to do this:
Power an electric winch

Which trailer connector do I need to match the minimum requirement?
Which trailer connector do I need to also match the optional
requirement?

I am under the impression that as a minimum, I should use 5-pole flat
connector and use the 5-th wire to connect to the reverse circuit in
my car in order to disengage the disc brake when the car is in
reverse. But there is one thing that I don't understand: The 5-th
wire (the blue one) is supposed to be for brake. Does this mean that
I don't have any more brake light if I use the 5-th wire for reverse?
Is that 5-th wire for "electric" brake that is irrelevant to me and is
OK to use it for reverse?

If I really want to use the electric powered winch, I need to go for 6-
pole or 7-pole trailer connector, right?

Sorry if these questions are too basic. I am very surprised that I
cannot find any info about these when I "google" or "wiki". May be I
didn't use the correct key words.

By the way, my car is a 2008 Highlander that can handle up to 5000-
lbs. And my boat is 18-ft fiberglass center console weight around
2300-lbs. I am not sure if these info are relevant or not.

Thanks for any info in advance.

Jay Chan