I guess I should have got involved in this a bit earlier
I have attached a pic of the tail of one of the P40's that I used to work on. Originally, the fabric surfaces were covered in a linen material which was stitched in place and then made tight using dope which was brushed on.
Modern materials mean that these days, stitching is not really required as the dope doubles up as a glue. Fabric certainly wouldn't be riveted in any way but you may be able to see rivets underneath the fabric which are holding the metal framework together. Hope that makes sense??
