Help needed for boom vang

[Berke]

Dear friends,

I have just finished building a motorsailer, Robert's PCF 40 and now I would like to make a decision how to trim to boom.we don't have a rigid boom vang and I am afraid we will not be able to fit due to the proximity of mast to the pilot house and it seems to me that there is no enough space for rigid vang, distances are:
- from mast to roof of pilot house 20cm
- from boom to roof of pilot house (vertical) 33cm
- from the connection point of mast and boom to roof of pilot house (diagonally) 40cm

Would you comment if I may fit a rigid vang?
...and if not what can be the solution?

Many thanks for your help

boom&mast | Flickr - Photo Sharing!