We took the Altun Ha tour with Daniel of Tanisha (a shorter version of the Lamanai tour), and would recommend him to anyone. If you want more time at Bomba, just ask. 15 more minutes won't be a problem, I'm sure. As a matter of fact, we had some extra time at Bomba because *someone* had a slight <ahem> problem, and needed to hang around the "comfort station" for a while.
Kathy