Yes, it is possible, but a lot could go wrong. It would help if you have a rental car already in the lot at the port. Waiting for transportation could slow you down significantly. Customs gets backed up quickly, so try to be among the first off the ship. Also, during some times of the time of year, fog causes frequent delays. Hobby is easier, both in terms of distance and traffic delays, but Bush is doable as well. Drive time is just under an hour to Hobby, 1 1/2 hours to Bush, not including parking, stops, or shuttles, etc. However, if you happen to be arriving M-F, those times would double or triple during rush hour traffic.