I think no matter what you do, you’re going to lose a good percentage of fish on Jigging Rap style baits. It’s a lot of weight in a small package, and a head-shaking walleye tossing that heavy slab back and forth is going to gain the leverage enough to loosen up the hooks at the incision site and create a hole wide enough for the barb to slip out.
It’s the same reason why a jumping bass can so easily toss a 3/4oz football jig or a 5/8oz lipless crankbait.
One trick I’ve found is to just horse them in on a heavy walleye rod like a Commander with a tightened drag. I have lost very few fish this way. The more they get the chance to head shake widely side to side, the better the odds of loosening the hook and tossing the lure. You just have to be careful when you get the fish near the hole because the front and rear hook have a tendency to catch on the ice.
I may try Bearcat’s suggestion. I’ve heard of that.
I’d also recommend sharpening the front and rear hooks. They’re disappointingly dull straight out of the package. They should be “fingernail sharp”.