ive found there is no such thing as a ground blind bow only a ground blind hunter. In other words its not the bow its the shooter. I use longer bows all the time and have no problem shooting from a ground blind. Shorter bows are becoming more common and they are mistakenly marketed as "great for ground blinds" if you design your blind the right way you can use anysize bow. Maybe im biased though as I cant my bow past 45 degrees.
Enough ranting though...
Get a stick cut to the length of your bow or the bow you hope to get or a bunch of sticks a bunch of different lengths and bring them into the blind and hold them like a bow and move around pretending your drawing the bow.
Just remember there really isint any difference in two inches of length.