surface protection for stove

You could try one of these.

https://www.storminstovesystems.co.uk/product/reflective-baseplate/

I went out again for just an overnight.  New cone, with more efficient stove, + heavy Duty aluminum foil= not melted plastic table.  The heat was directed upwards as it is supposed to be. The heavy duty foil was doubled in thickness. It was colder than other trips that I’ve had this summer, so that might have had something to do with it as well.

Looks like you have confirmed that the melting is due to radiated heat from the cone and bottom of the pot rather than direct conduction form the stove.

Nice cheap solution.