Just a thought...with due regard for your avatar TX, I find that my wife's 637 add's no significant weight nor unbalance my already overloaded fly vest while trout fishing. I built the left side, armpit, muzzle down holster for it and sewed/riveted it in place. I also like the aluminum framed, SS bbl'd 637 as it's more resistant to sweat and the twice yearly dunking when I take an inadvertent dip in 60 degree water.
With the same revolver choice (Aluminum framed etc), an alternate carry position would be the front pocket of your waders....which I've tried, but found a PITA to get to when I practiced my "presentation". Additionally, I tried my usual OWB, 4 o'clock hip carry on my wader belt, but quickly found that deeper water, and/or a quick 'sit-down' to preclude a complete fall, dunked the gun far too often.
Rod