Have I got a warped bed?

Yes it looks like you have a high center. Your glass looks to be rather thin. It should be 6mm or 1/4 to avoid following the warp in the bed. You may also need to look into getting the aluminum stiffeners for the L brackets that the bed mounts to.

I am not printing on glass just Kapton.

Spray the bottom of the glas with a heavy coat of Aquanet extreme hold unscented.  Stick it on your build plate.  Heat cool cycle 3 times.  The hairspray will bubble creating a little micro shims.  It’ll stick very wel yet still be removable.

Move your bed to the bottom.  Cover anything near the rear that your worried about with a rag.
You only put a lite mist on the bed and only redo it every few prints if needed.  Don’t be dumb about how you spray and get it everywhere.  I have used this method for over 5 years on one of my enclosed machines.  Never has there been any adverse affects.  But, I am careful to not spray everything inside and simply point at the glass.

Adding adjustment to your Z endstop is always a good idea.  It affords you some flexibility to experiment.