you could find somebody parting a bed that can sell you a portion of the floor...or you could buy the smallest bed patch you can find...
https://www.amazon.com/Bed-Floor-Rep...132798&sr=8-18
if you want to keep access - I did see a guy on youtube make a floor access panel. Let me see if I can find a link.
Link added =
https://www.youtube.com/watch?v=gFkRO9Wtvdw