Yes ports can stick out. The reason most people don't do is because it looks weird. In your case it doesn't really matter because its going into the bed.
coversion technics like swappable ports and sealed plates ...i made a joke once on this subject about making header pipes using this approach ...if you were using one sub you could make one functional and the rest nonfunctional to create the appearance you want and you could paint the pipes or use whatever material you wanted heck how bout a mock up motor with those pipes lol ps...as you said you could also port into a cab or up through a deck depending on your project goals this is without the header pipe idea used of course hehe
that is awesome...i never knew that you could hvae them come out that much...so if you needed approx 16 inches of port, you could have a few inches stinking out if you couldnt fit it all in the enclosure?
just remember that box volume should account for port colume as well as driver displacement. Moving the port in and out of the box affects the amount of volume the port takes inside the box, thus affecting the box's net volume for air space.
