Hmm. Have you considered hanging your Compound #5 in front of the lens? I hang one in front of my 900/10 Apo Saphir using an adapter that SKGrimes made for me. I did this because the lens' barrel is so wide that it will prevent access to the controls of a Compound #5 when the cells are mounted in it, also when the shutter is mounted behind the lens.
Re weight, the OF-233 weighs 2.2 kg. Not that heavy.
The Compound #5's maximum opening is 64.5 mm. The OF-233's entrance pupil's diameter is 84 mm. Depending on the lens pupillary magnification, using a Compound #5 may cost you more maximum aperture than you like. Consider mounting the lens in front of (or behind) a large Packard shutter.