How to deal with people who dig their head in your stomach and then work your

Again, no expert here. But I can tell you what works against me.

But being a shorter guy - i'm sometimes the guy with his head on your chest. Some people let me stroll through the front door.
Other people punish me on the way in and make me think twice about crossing the line.
So one of 2 things is happening:

1: I'm walking straight through, unpunished in a tight peakaboo guard - you need to stop my entry with jabs, hard uppercuts and circle out.

2: I'm throwing soft jabs to get in - don't fear the soft jabs, back up and look for opportunity to counter.

3: If i manage to get through, hunch your shoulder under my chest and shrug me back.

Not sure if others would agree, but these are ways to get me off your chest.