HIPS is my favorite general printing material.....but my least favorite when dealing with supports like what you show.
1. HIPS is very soft/waxy, it's easy to drive/smear the support you're trying to remove into the base part (by scraping for instance). Once it bonds like that, basically can't get it off cleanly. Only peal/wedge away the support from the base part.
2. Before removing support, place the part in a freezer.
3. Play with fan speeds/covers
4. Change orientation (if you printed your part vertically, would have way less support area required)
I print a lot of these and it costs me a lot of time to remove the support with a sharp knife.
For sure 6 month ago (so lot updates ago) it was very easy to remove the support by hand.
Can i change something in the design? I am thinking about creating a second plate and a small gap (0.19mm) between the shape i want and the shape which touch the support.