Help - Need Water Tank Fittings

I have just built out the back of my land rover (photo attached). I am going to mount a water tank in one of the boxes and want a flush mount water connection that doesn't cost the earth.
Does anyone know of anything. The section underneath the sleeping platform will be used for storage in and out so don't want a water spilling everywhere if a box catches a connection coming out of the box, hence wanting something flush.

Why not fit a standard hose type connector but recess it slightly but cutting a hole and making a small box behind.