Great write up and idea. I am thinking of doing the same thing.
Please clearify, for the rear hole, you don't need a braket right? and for the front, you are not using the stock hole that angles 45 degree right?
i am wondering is there any aftermarket braket/rail can be use as a adaptor.
Thats correct. The back fits in the stock holes, no need for a bracket.
The fronts I used two existing holes (not the ones on a 45) and bolted all the way through.
Let me know if you have any questions. I took more pictures than what I posted, if you need any specific ones, let me know!