Go for the high position.
I have two lights mounted on my A-Frame and they give good light.
I find at night when underway your better with them off, but they are great when you have to do jobs at night of need to pack things up in the dark.
I have then angled down to shine on the engine cover, which is bright yellow.
Your geet good light but dont get blinded everytime you glance at them.
I use the submersible pond lights from RING.
My reasoning is if they spend their life underwater they should survive on a RIB
But be careful some are only rated for use under water where they get the cooling from the water.
Think mine ar 20W each and give more then ample light.