Everyday: As fishawn asked, could you please clairify what you mean by this "trailing hook set up"? I know you are big on sickle hooks.
When I first started this set up (maybe it was done somewhere before me?), I always TIED the braid to the hook. I like using my fly tying stuff (all you need is a vice, bobbin, thread hook and some braid) to create a loop on the hook. Tie the braid end pieces down to the hook shank and form a loop at least 2 inches long above the hook. Then you use the bottom hole in the spoon and create a loop to loop connection.
One of my buddies didn't want to take time tying up hooks, so he just uses a piece of braid, runs it through the eye of the hook and does something like an albright knot to tie the braid to itself. It works, I just don't like how it rides in the water. I also feel like my way of rigging is stronger.
Everyday:
Any tips you would be able to offer as far as hooks, rigging (swivel, knots, duo-locks etc), line, etc would be awesome
I tend to run lighter set ups for spinning for all fish (when I say all, coho, steelhead, chum). I like to run rods rated 6-10 or 8-12. I like soft rods (fast action) so I can feel a good kick on the swing. I always run braid, 15 pound. The white floating stuff is great cause you can actually mend it and control your swing better, also super visible from above water, and not so much from under water.
Like you, I did much experimenting, actually even on the L2F ponds when I worked there the past 2 summers. I found the trout responded much better to flouro when compared to mono, and better to mono vs braid. These fish were as dumb as the get and I still couldn't get one with braid straight to the spoon, they just wouldn't touch it.
At this point I run braid and a modified perfection loop or albright knot depending on how I feel to 10 feet of 15 pound flouro. The knots sliding through the guides does nothing, in fact, it doesn't even affect casting distance in the slightest from what I have found. Duo locks are great for what you have described - keep using em!
Never found a baitcaster to be an advantage when tossing metal. I prefer spinning reels. I just adjust spoon size or how far upriver I cast accordingly to current to keep the spoon down. I always try to let my spoon roll bottom two or three times before I start my swing. I feel letting out bursts of line totally goes against the covering water aspect of spoons. Do you see many guys spey or fly fishing let out bursts of line or taking steps down on their swing? A spoon is heavier, so realistically, why would you need to let line out. I have also watched steelhead in -10C from a vantage point rise up to spoons 2 ft under the surface in 10+ feet of water, and sometimes chase for 50+ feet. Just because it's cold doesn't mean that they won't move.
Leave the float rods at home if you want to get good at metal. it's a steep learning curve (swinging spoons) and you won't get anywhere unless you put a bunch of trips in to get a good feel for it. IMO it's the most effective way of covering water, and in the past 3 years of sight fishing island rivers, only a handful of fish I have seen didn't take a swipe... the other couple hundred (summers or winters) tried to commit suicide on it. It catches fish and is very under utilized.
Good luck!