A fellow MX300 user from Italy sent me some pics and notes of his very interesting custom-made camera bracket/mic holder and rain jacket. The bracket accomodates a shotgun mic and uses the belt battery as a counter balance.

Have a look;

http://www.mycen.com.my/dv/bibo.html

Thanks Terrence for making this info available. I contacted the fellow and he was very helpful. His mount seems promising.