Fenn (old school) cable connector bolt fail..

Any decent tips on getting the stripped bolt out?

Soak it over nite in a product like Blaster and then use a pair of vise grips.

Use a easy out

Chances are if is stuck enough for the head to shear off, you will not be able to turn it with what is left of the bolt.
If this is on the boat, I would put a piece of wood under it. Have someone use a vice grip to hold the connector steady. Use a file to smooth out the top of the screw. Use a punch to punch the center of the bolt.
Get a "left hand drill bit". They are harder to find than regular drill bits. Left hand drill turns in the unscrewing direction. Drill down into the bolt. As you are drilling, you will need to tilt the drill to walk it back to the center as it gets off center. Very important to get it to center.
Decision is either to go up in drill size until it comes out or try the easy-out.

You’ll be replacing the rusty cable right? Spend ten bucks and buy a new cable connector from Ocean Paddler. You could really spoil yourself for twenty bucks on a matching pair.
oceanpaddler.com/online-store/fenn-cable-connector/

After first removing the other screw I've always been able to get the broken screw out easily with a pair of pliers. While at it replace all 4 screws with M3 grubscrews.

You nailed it Atlas. Three other bolts likely to be compromised plus rudder cables themselves clearly rusting out. Replace the lot.