Design help

[Willyou]

I suggest doing some research on the different expansion rates between the two different woods.

Locking them together by simply screwing them together could lead to problems down the road. 

Do you have a moisture meter?

Walnut has a Tangential % of 5.5% and a Radial % of 7.8%  Whereas Zebrawood has a T% of 8.8% and R% of 11%.  So the Tangential value of Zebrawood is 50% higher than Walnut and the Radial value is over 40% higher.

A cracking problem is not assured but IMO, it is also not out of the realm of possibilities.

I think it is assumed that the OP is applying screws through elongated holes or using clips designed to accommodate seasonal movement. This is the normal usual practice which has been used successfully for many years. His question is regarding space limitations he has for driving the screws.

[iublue]

I think it is assumed that the OP is applying screws through elongated holes or using clips designed to accommodate seasonal movement. This is the normal usual practice which has been used successfully for many years. His question is regarding space limitations he has for driving the screws.

I don't assume anything. 
Kreg screws were mentioned in the thread and as far as I know they are not movement friendly.