Until it has been succesfully accomplished, tread lightly. I am not saying anything bad here, but it is a total redesign.
It shouldn't be any issue, but you can never be too safe.
I guess what I am saying is that you don't want to go borking up a brand new board. This is not saying anything bad about the product or anyone attempting this. Okay? :) Just that it really wasn't designed with that in mind...
And yes I have a recharge port on an Ultrasound right now... But given the issues we had with reverse voltage on the Ultrafire non-protected batteries and people frying their boards the first time around... You get my point.
Hooking up a port needs to be done right... it was merely a cautionary tip more than anything else, for those less experienced in doing such things...