No filter in the tunnel.
I have 2 filters, one under each seat and no access cover.
Filters in this position are very easy to service.
Fuel pump and red cube are in the tunnel and rarely need service.
I did have a problem with a leaky red cube and needed to remove it from the tunnel. There is no way that could have been done through an access hole.
I also cannot imagine inspecting the tunnel with only an access hole cover removed, so for at least the annual condition inspection the top cover should be removed anyway.
However, I am sure the cost and time investment for an access cover is minimal and may come in handy at times, especially for those that have instrument panels extending all the way down to the top of the tunnel cover.