podunk, i have used tip-ups all my life and done really good for pike and trout. i have caught many types of fish on them thou. as fuzzyfishin said, the fish feed up. a good rule to follow for pike is 3ft. off bottom or the structure that you are fishing. sometimes you might be 15ft. off bottom because of a break that you are on. i have a spot like this on gull lake that i get some mighty big pike off of. a sand bar comes off one end of an inland and goes out into 70ft. of water.
the spot that i'm talking about is the bar is 12ft. on the top and there's a slot on one side that drops to 30ft. i set the tip-up just over about 15ft of water on this slot, about 10 or 11 ft down.
maybe this will give ya a better idea. when i use to spear on this spot the 12ft. mark was about 3-5ft from one side of the dark house and the 30ft of water was on the other side. and the darkhouse was sitting in 15-20ft. of water, the full length of the spearing hole. i would put the deke about 9ft. down. had many pike come off the shallow bar and i had watch them come up the slot right to the deke.
for walleyes set bait/minnow about a ft. off bottom like you would fish for perch. sometimes you might have to make it 6", sometimes a couple of feet. it depends on there mood.