Well, mounted high enough, I don't think the fan would create enough turbulence down below near the basket to kick up ash. Even in a kitchen oven these fans don't seem to blow that much air, but just enough to circulate the hot air.
I would also assume the fan will raise the temperature somewhat but you can easily regulate the temp as you would normally do with the vents.
When mounted against one side of the UDS small, low profile deflectors can help protect the fan assembly from radiant heat and from drippings.
....UDS....Mini-WSM....Midi-WSM....Mod-ECB....22.5-OTG....34"wood fired pizza oven....