You can't thin an elastomeric paint enough to spray with a .015 tip. The 3/8" hose is OK as long as your airless sprayer is strong enough to push the paint. Add a small amount of water, 1/2 gallon per 5, and use a .021 tip.
Make sure to remove the filters from the pump and the gun. This will help the pump push the paint.
Many elastomeric paints can be used on wood surfaces as well as masonry. Check with the manufacture specs for recommendations pertaining to your product.