dude i hate to say it but i have moustache bars that i ditched after about 10 rides. to me they really only give one hand position and after about 15 minutes in that postion no matter what i tired the hands went to bed.
i tried various angles but nothing ever worked. now they hang in my garage and i use mb riser bars on the fixie and regular bullhorns on the other commuter.
there is also a reason roadies ride drop bars i am quite convinced that once set up properly they are the most comfortable and offer the most hand positions.
i am going on a REALLY long ride soon and plan to install some (salsa bellaps) with a nice high rise stem and wrap the bars with some nice extra tape under the flats and hoods. all in all i think that is the best way to achieve comfort for the long haul.
maybe it is your back but i bet rasing your bars higher will sove the problem (unfortunatley with moustache bars that comfortable position is really freakin high for most people).