Since you will have access to the roof,I would think that an antenna like a G5RV mini would work fine they are a 40 to 10 meter dipole that is about half the over length of a full sized G5RV ...and I would think that 16 inches to 2 feet off the ridge of the roof should be fine....
I am sure there are more folks here that know more about this than I do though.....that is my personal thoughts on the antenna for what its worth
I am sure there are more folks here that know more about this than I do though.....that is my personal thoughts on the antenna for what its worth