What I've seen, 4-pin flat connectors are used more than 5-pin rounds. So if you buy more trailers - like a Tagalong, either the Northern Tool original or the HF ripoff, they come with 4-pin flat. So does the HF flatbed trailer, The Timeout camper, and my enclosed Cargo Mate.
I added electric brakes to my Timeout camper. It can get around 600# with all the camping gear I like to add. Like A/C and cooking equip, toilet, lotsa lights incl 2 gas lanterns and several LED ones. A really comfy self-inflating queen size bed mat. All those toys aren't heavy individually but they add up. Timeout sells the compatible electric brake kit. Including the Tekonsha controller.
Some folks say put the controller on the trailer. Like Jersey, I agree having the controller adjusters where you can reach them while riding makes adjustment much more convenient than where you have to stop, get off, make an adjustment then resume. I mounted my Tekonsha on the handlebar under the Escort radar unit. It's shielded from weather by the tipped windscreen.
However you wire for electric brakes, separate from 4-pin flat or within a 5-pin round, it can be treated independently from the light controls. Wire the pin or not (5-pin round), add the extra 2 wires for the brakes or not (4-pin flat), as you need.
I set up the lighting with a 4-pin flat plug. Wired the brake/turn conversion myself with 2 relays I have documented elsewhere on this forum and my tech tips page. This is an easy mod to implement for anyone with a modicum of electrical skill like soldering, and it's easy to maintain as it uses standard inexpensive 5-pin auto relays available at all auto parts stores. The diodes and resistors are not needed if you are powering 1157 type lights (2-filiment). I added a separate 2-wire plug for the brakes. This setup is compatible with the same 4-pin plug on my Tagalong, HF flatbed trailer, Cargo Mate bike hauler and another flatbed bike hauler I made myself, and 4runner and CX-5 so they are all compatible with each other. The Mazda I wired a similar conversion with 2 relays that I used on Jade & Deerslayer. The Toyota is already compatible with no mods. In fact it supports a round connector as well - I don't use. OK I'll attach the diagram describing that circuit as used on the bikes (except with 1157 sockets). Modify the output side of it to support 1157 (2-wire) bulbs - that's even simpler, the circuit isn't involved with powering the running lights. My bikes all use this circuit to provide run-brake-turn lights out of the rear markers, while I have installed 1157 sockets in back, and clear lenses with red LED array lights - 1157's are what all trailers (that I know of) have. But the bike comes with 1156's so you can use this as designed if you want to, for RBT lights on the bike while providing the correct circuit for your trailers.
