I have not been fishing the same lakes as you but here’s what I have found lately on some area lakes. Just about every walleye I’ve found has been holding tight to mid-depth weedline edges, 12 to 24 feet, depending on the lake fished. I also noticed that the walleye were very tightly grouped, so much so that I decided to stop and jig several times instead of pulling spinners. Both spinners and jigs (yellow/chart) tipped with fathead minnows worked well. Slow troll, maybe 1.5mph. I fished day time only but reading some of the reports on here I would say give the night fishing a shot pulling shallow running cranks over shallow humps. Read James’ report and apply his tactics. No reason it should not work on Ottertail just the same. I’m going back to Battle again on the 18th and will try some night fishing then myself. Best of luck and have fun!