Disaster struck my build today

!!
I had to remove the bottom base panel as I had cut it too long for the door to fit flush against.
Unfortunately I had secured it to the frame with carriage bolts, got 3 of them out then on the last one it split the MDF

!!!!
So I cut a new base to the correct size, well what I thought was the correct size, it turns out that its about 2-3mm wider than the last base.
This now makes my kick panel have a gap on one side that joins to the side of the cab.
I'm sure that this wont screw in place as the pressure will pull the screws out, whats the best way to fill this gap?
I don't think filler will do the job as its to large and will only end up cracking, breaking etc.
It took me too long to make the kick panel and I've secured the new base in place once again with carriage bolts so I really cant make any new panels.
Any advice will be greatly appreciated

