Magnesium is your friend here. There is a product called natural calm that is basically flavored magnesium citrate. Keeping upping the dose on this until you get to the pooping out water big macs from 1984 level of pooping then back it off slowly till you achieve the consistency you want. Usually it ends up around the dose on the bottle or slightly more. Fiber has nothing on magneaium as far as fine tuning the water content of your poops.

MiraLAX (or any of the generics) three times a week does this for me, and according to my doc is safe to drink for the rest of my life. Good luck soldier.