Open Rain Screen questions – GreenBuildingAdvisor

  I am part way through building a 1000 square foot PGH in coastal maine, 6A.  I have double stud walls and the original plan was to go with a closed rain screen.  I have 2 foot overhangs and zip sheathing, partially taped at this point and my windows are in.  I milled up a bunch of 1×8 spruce from trees on my site and its dried and ready to go, installing it untreated.  I am considering switching to an open rain screen (for air around the boards) with 1/4-3/8 inch gaps and wanted to see if it is possible to switch to an open rain screen at this point in the project. I will either use 3/4 or 1/2 inch battens on 16 inch centers and place my siding horizontally. 

 Because i have zip and intend to finish taping it (and my windows are already taped to it) the question of how to get UV protection is at this point is my main concern.

1.Could I simply fasten some Fassade S to get the UV protection i want without needing to detail it as a traditional wrb? How about horizontal swaths of black UV paint applied to the zip where the gaps will be as a cost saver?

4.Finally, has anyone ever done an open rain screen treatment of a soffit?   

Thanks, Stephen