I am not endorsing this product and have not used it, but have read about it. Maybe it would be a possibility.
http://www.benjaminobdyke.com/visitor/product/key/homeSlickerIf you don't like this product then furring strips seem like the way to go.
You are installing the shiplap horizontally? The reason I ask is because I don't understand the need for weep holes in the furring strips. If the furring strips are laid horizontally for vertical siding like B&B, then I understand the weep holes.
If you really do need weep holes, and don't like cutting them, there is a corrugated plastic product that some people use. I personally prefer to have less manufactured products, but just passing on a few options.