Fortunately, at this point I mainly need to concentrate on rigging for foot movement. Within a few months, my unit will be a newly "transformed" LRS company, so I am expecting and looking forward to lots of long rucks.
Right now, I've got the FLC adjusted to a sort of compromise position where it seems to interfere with the ruck the least. I can't quite bring myself to remove my canteens. Maybe I'll change my mind after I have a chance to try it all out in practice, but I'm having a hard time with the idea that I would have to keep moving my Camelbak in and out of my ruck/assault pack just to have water at all times. I think the most simple solution may be to add some length to the suspender webbing in the front, so I can drop the FLC down lower, without the crossbar riding up as much.
My duty position involves a lot of the crawling and laying in the prone, so I'll also have to see how much the pouches interfere with that.
I would still be interested to hear if anyone else has any suggestions.