RB-alu side housings, make it a P-port and you are way ahead of the weight-game...!! 

 

The first problem with that plan is that the RB housings essentially don't exist.  They've never finished the front housing, and have only sporadically offered rear and intermediate housings. I just called them again a couple weeks ago, and they told me the same thing they've said for at least 3 years- "we're working on them, and they should be ready soon".    

 

Rusty