I use several items for different situations.
For Back Country is a wading vest and a small day pack to carry extra gear/ lunch etc. I usually totat a quart of water as well.
For Semi close trips I use the wading vest in winter or a lite shoulder pack. I really like the shoulder pack the best for it is light and has more than enough room . I use the Filson pack that has a front bag and a rear bag.
For real light days I use a real old Army open pouch just enough to hold the essentials.
I have looked at the fish pond products a they are simular to the Filson pack with a front and rear bag. I think you would be happy with the down sizing.
I agree wihe the above comment that by human nature we fisherman want to carry every thing we have but we can break that habbit by just carrying less.
Hope some of this jargan helps.