Can you have a 6th order bandpass with visible subs?

If you want the driver visible, I would choose other designs. Even viewing through a port has issues; bigger ports need to also be longer for most subwoofer tunings. Which would make the driver harder to see, probably make the box rather long as you couldn't bend the port, take up more space and tend to introduce pipe resonances at lower frequecies (close to the pass band).

By contrast many (possibly even most) other designs have the woofer on show by default, for no extra work needed.