Hi Monkfish81;
It's so convenient and clever for you to set an extra deck hatch opening at rear as you may know that adjustment of tiller arm is normally made frequently until best position is decided/found through many trial sailings, from my experience in the past.
What is worse, the best position to be considered at one time could be apt to change sometimes due to some reasons. Furthermore,preliminary checking of the fixing screws of the rudder post /tiller arm will require this opening every time before sailing.
I am looking forward to seeing your sailing pics on here.!!
Stay safe
Cheer
Kiyo