Thanks for looking in, annnnd all the comments!!!!
So today I filled the cavity in the fuselage at the flaps.
I used 2mm thick styrene, made wedges and glued them in.
I then filed and sanded them down
and now the cavity is filled ans smooth.
I had to replace the seat, just too big!!
Added some more goodies, both side panels,
stick, throttle box, odds and ends.
Have pre-fit the IP, peddles and other stuff.
On and on.