The issue with trailer light connections is both simple and complex at the same time. I will contradict Dom.five's statement that Honda's wiring is not up to the task of merely spicing from the lights by telling you I did it on my Element seven years ago, regularly pull a trailer, and have never so much as burned a fuse. I've also added additional quartz halogen back up lights and "third" brake lights by merely tapping, with the same consistent no-problem results.
That said, I have no problems because all my trailers have separate amber turn signal lights, plus back up lights! Also note, I have never done Shen's infamous turn signal mod (which messes with the ground circuit in those lights), leading to direct failure in trailer light schemes which don't use the official Honda trailer pigtail. I added my own amber turn signal repeaters to my front fenders specifically to avoid that problem, and because I think they look great besides.
It's a tossup as to whether it cost me more to add the amber lights and wiring to my trailers vs. the cost of the Honda pigtail. BUT - you have to choose one approach or the other. You can't mix and match or be lazy about it.
I prefer the consistency of all my turn signal lights being amber, so as not to confuse the horde of moron drivers behind me. I also have absolute faith in my ability to perform reliable and safe 12 volt DC wiring. Lacking said ability, it's cheaper in the long run to have it done professionally.
I chose the additional turn signal lights for my trailers when auto makers first began adding "third" brake lights, separate amber turn signals and circuits in the first place, knowing I would be keeping my trailers for years beyond any car I had at the time. I also chose a scheme whereby the plugs on my trailers can also be used with vehicles that don't have separate brake and turn signal circuits because each trailer retains its original (cheap-ass) American combination tail-brake-turn signal lights.
Bottom line: If you choose to not invest in adding turn signal lights and wiring to a trailer, you had better not do Shen's turn signal mod, and you absolutely should use the Honda harness pigtail. If you don't know how to do this kind of wiring (and panel removal to get at it), be prepared to spend more to fix your mistakes than what it would have cost to have it done professionally in the first place.
This forum is great for information and hand-holding, but not very efficient at fixing a botched wiring job after the fact. Think hard before beginning to do a project like this yourself. I'm ashamed to have used the word "you" in this reply in a grammatically incorrect fashion, but it was much simpler to do so. However, please understand that "you" does not refer to anyone specifically in this thread; it simply refers to "any generic person".