I looked into the SDL situation a little while ago, it should be possible to build an SDL that has both the bvdd and qtopia drivers. The driver that a particular game uses could be selected by setting an ENV variable..
The only problem is that some of the names used in bvdd conflict with the qtopia driver, so I'm guessing they would just need to be changed to be unique.
I'm not that familiar with the zPorts SDL, so I don't know what driver it is using.