Sorry your outing wasn't very productive. On the bright side, like you said calm water and wildlife viewing can make up for an otherwise slow day on the water.
Here are some additional thoughts. I never use dodgers with my flies on leaded line. I never run anything, leaded or mono, more than 250' out - it's just not necessary. I run 50' of 6# leader on my leaded line rigs, and using line counter reels, send my Frisky Jenny flies out 150' - 155'. The mono rigs are also equipped with line counter reels. My trolling speeds are 2.5 - 3.0mph, with 2.8mph my most normal speed. Wedding type rigs requires a slower trolling speed, and I don't like trolling that slow. Needless to say, I hardly ever use that gear. I never
troll in a straight line, you need to turn the boat, especially on calm water days. One local guide used to call it "the drunken sailor" and that's what I do, drive like a drunken sailor. I prefer
overcast days with a good wind chop over clear days with smooth water. Raining or snowing is even better.
I have Sidewinder
planers, but have only used them a time or two. They work well, I just don't like dedicating a rod to use them since they require the line be run through them before being passed through a bead and then tied to a swivel. If I want to use the same rod for long lining a plug, I have to remove the sidewinder to do so and I don't like tying and retying in cold weather, so I refrain from using them. Having said that, they would
allow you to shorten the amount of line you have out, say 35' - 50' back from the sidewinder and about 50' to the side. These would work good in a 12' open boat.
Using a wiggle fin disc in front of your flies is a also good suggestion. It adds action without the need for a dodger.
Unless you want to watch bottom contour, forget the fish finder, it won't help you locate the fish. I rarely mark fish unless they are 35' or deeper. That's because the size of the sonar cone at the transducer is so small at 10' deep, the fish would have to be directly under the transducer at that instant
in order to show on the display. When the fish are in the top 10' of water, they scatter to the side of the boat as it passes over, well outside the sonar cone. I can be into the fish non-stop, and not mark a single one, all because of that. A side scan sonar would be nice, and absolutely would show fish to the sides of the boat, but the price keeps me from putting one on my boat.
You're welcome to PM me anytime.