To have, or not have, a hatch is your decision. If I build without a hatch, I make sure there's some type of access to the tank. If it's a tight fit, put some filament strapping tape around the tank and leave extra for a pull. Having a hatch makes maintenance easier, but it better be a snug fit, and make sure the exhaust has an extension to minimize fuel seeping in. <div>
</div><div>The Tango ARF is a good (read: bad) example of how not to build a tank enclosure: fully enclosed, a 1" hole in the firewall for the tank cap, fuselage formers that are tight to the tank, transmitting every vibration to the fuel. It's a fun, goofy plane, but some areas of the design make one wonder. </div>