Wow, you know your stuff. You fished it pretty much the same way, that I'd approach a new lake in the early season.
I have had great luck with a green and black wedding ring, tipped with a 1/2 night crawler (and a Ford Fender or Doc Shelton). That rig has produced well, in Foster and Green Peter. So, I'm hoping to try some other lakes too. And I always try a brass colored Little Cleo spoon/wobbler. That lure produced more fish trolling last year, than anything else.
Next time that you go, I'd encourage an attempt w/ your fly rod and Woolly Buggers. They almost never fail, and it should work well from a row boat.
Thanks for your report!