Bob,
When the water level drops in a pond or lake, it is frequently terrestrial (land based) weeds and vegetation that start growing on the newly exposed pond bottom. This does provide excellent cover for forage species when the water levels go back up and re-flood that vegetation. However, that is a short-term benefit - those terrestrial plants will die when flooded. (I think your edge grass plantings would be a poor investment.)
I do agree with your next to last sentence. You don't want your GS gobbled up immediately, you want a breeding population with places to hide and thrive and are only occasionally gobbled up!
I personally (non-expert) would agree with transplanting some beneficial water plants during this stage of your pond management. However, I suspect there may be some rules against taking plants from state lakes. (And they could have zebra mussels.) Try and look up the rules, or ask a park ranger.
Any buddies with ponds where they would let you harvest?
