i'd go for it with the FL gar too Conner...you should see some nice growth and coloration develop on all your gars that you put out there. just be wary of any threats to the pond/fishes...sounded like everything was pretty well under control though.
as for hunting times...gars, like many other fishes are crepuscular hunters, which means, like you guessed, they are hunting most actively during dawn and dusk...the lower-light periods of the day. they will also feed at night, but also use night for greater movement (distances traveled in most cases) in the wild.
in the wild, mid-day gars are usually staying in generally one place/area--
--solomon