You will still need a basking area, water heaters and water filters. I think water heaters are absolutely necessary because water temperatures can be unpredictable in small amounts. For filtration, you can choose a large canister or a pond filter. I have no idea what the media options there are for pond filters, maybe RES Tampa can chime in

Canister filters have extension tubes, so they should be fine to use.
A protective enclosure would still be necessary to keep your turtles in and predators out.