Personally I never had problems with abs, although I used to bust out like 50 jumps per sesh.

But if you are the less athletic type and want a "pussy solution", you could also go with a seat harness.
It brings some other downsides, like a bit less freedom of motion, edging ability not as good, and a bit of a weird feeling in jumps cause you are kind of sitting in a sling.
But it is gonna be easier on the abs, and most of all on the lower back.
And especially if your edging ability is not great you should be able to jump a bit higher with a seat harness, because you could just lean back and use your bodyweight to counteract the power of the kite.
Which is however not a good technique, so if you are serious about progressing, keep the waist harness and htfu!

The soreness is gonna go away quickly anyway as the body gets used to the new task.