A 75 and 120 sound good! Make sure you have a powerful filter and do a complete water change often because of their poop bacteria like Salmonella can build up in tank. As for the other question about housing a Florida softshell outside, and the answer to that is I'm not sure how cold it gets in Virginia, so I don't know. Maybe yu can house it outside during the summer month and bring it inside in the winter if it gets cold. How cold does it get over there? If you house it inside, no heater is require for softshell turtles, but you still need a basking light for it and place where it can completely haul itself out of the water to dry off and bask.