LM27403: moving thermal vias out of pad

I'm using an LM27403 controller in a 12V-->3p3v application. As the Lm27403 is the only part on the board with via-in-pad I want to move the thermal vias out of the pad onto the board to avoid epoxy fill or taping the vias in production.my layout looks like this:

the stitching vias on the ground poly sink into a board-wide ground plane. This should be more than adequate electrically, but am concerned about thermal issues. 

Is there any guidance that you can provide in this regard?

thanks