On thing that can be done is to use Lead Core line. First thing you will have to determine will be if the boat is spooking the fish, therefore requiring “long lines” to get the lure away from the boat. One of the downsides of Lead Core is that you will be running the baits a lot closer to the boat. But we have had many instances where even in 10 feet the boat does not bother the fish much and we can troll right over them.
An advantage to long rods is that they get lures away from the boat – reducing spooking. We came out with a set of 12 foot rods specifically built for walleye fishing – one of them is the 12 foot Trolling Rod which can handle the pull of Lead Core.
Now for the reasoning behind Lead Core. Many people think of using Lead Core (weighted line) to get baits deeper than they can dive themselves – which is one of the uses. But another thing lead can do is help your baits following the changing depths.
The way it works is, you will be running all Lead Core line (I use 18 pound Magibraid from Bass Pro Shops) except for the last 10 feet. The last 10 feet is a leader of 10 pound Berkley FireLine.
Start trolling at the desired speed in the target depth (in your case 10 feet) and put out enough line (leader and lead) to just be ticking bottom in 10 feet. Now, if the bottom all of a sudden gets deeper, you can slow down your motor and the leadcore will dive more effectively. With the short leader, the crankbait will follow the lead and start fishing deeper. I would guess you could get almost another 5 feet out of it.
Conversely, if you go shallower than 10 feet, speed up your motor a little. This will cause the leadcore to raise up, the bait will follow and you can fish shallower.
I know it doesn’t cure the getting out to 30 feet problem, but it can greatly increase the amount of time your bait is close to the bottom.