The only areas that you may want to delay or customize access is the rear seat and baggage area.
A fair number of people mount antennas under the rear seat. I ended up making an access panel (after the fact) when I had to troubleshot an antenna issue.
The other area is to access the bolt for the steps. Nuts have become less tight and needed to be re-tighten. This doesn't seem to impact everyone, but it does appear to happen frequently. I installed some aluminum pieces that Bob Newman (TCW Technologies)
made which appear to minimize that issue due to having something solid to minimize the flexing.
I also held off riveting the upper fuselage assembly to give me more time to work on the wiring harness. It's much easier to wire on the bench that in the plane.