Like the others said. Those numbers are reversed most likely and the span between them could be difficult. When we test we actually will go 20 feet or more above the roof line. That way we know if a tripod is an option or if not then the customer at least has an answer on how high is needed with a tower to get service. Some customers have searched out there own antenna towers (used) and installed them for us. We come back climb them and install.
If you willing to go through the work of installing an antenna tower then tell them so and let them know you just need to know how high it needs to be.
If they are not willing to discuss those options with you my advice would be not to pursue internet through them.