Finn the best place to install them is the furthest you can from the hinge. Less force needed to hold hatch open. So get some long ones and then fit them were they fit

If you draw a plan of them (when you get them) and the hatch you can figure out where to put them so they hold the door shut too.
Didn't get mine right but was close enough, they try and shut the hatch when it id about 18" open. But this is OK as when the hatch tries to slam shut the air trapped inside gives it a soft shut.
WarPoney
You sure that cat didn't rip that wood up? Mine always look innocent like that when they have done something wrong.
What is it about cats and workshops, two of mine are always under my feet or lying on the bit of wood I need whenever I'm working.