Two tricks I use...
1. I like to pull out about 15' of tip-up line and re-wrap it toward the top of the spool. That would be the top if it was sitting in the water.
Wrap it along the top as close to the spool wall as possible. This will allow the line to build up some in this area. Then when you know the depth you want, take the line and pull it tight up against the spool wall. This will wedge the line between the edge of the spool wall and the build-up of line. Try it once or twice to see if it's in there snug, but not too tight. Then put the line thru the guide and place it in the water. It's worked for me for years. We've used 8"-10" chubs and this keeps them from sending up a false flag. Will work for any sized bait and any kind of mono or tip-up line.
2. Figure out the depth you want the bait. Take a thin medium size rubber band and wrap it around the line and back thru the rubber band. This will attach the rubber to the tip-up line. Then loop the rubber band in the line guide on the tip-up. The bait can pull and pull but the rubber band will only strech. Until... the bait is hit and the rubber band breaks and the spool can spin freely. Fish on!
Just my 2 cents
Good luck!
G-MAN