I think there will still be plenty of lift. I forget the measurment, but I want to say it's over 50" from pad to prop. When I moved my
2.5 2" closer it didn't lose any lift, just better low speed handling and manners. 2.5 liter at 12" felt very similar to 3 liter at 8.5". I gained speed coming in, which is why if I had an extra 1500 laying around I wanted to try less setback. On the other hand I will be able to move batteries forward quite cheaply.
The end of pad/lip is completely in front of gas tank. So moving the batteries from a foot+ behind the pad to 1 foot+ in front of pad may do the trick.