Just for info!!
Using Body filler in the seams is a VERY VERY VERY bad idea!!
No matter how much you weld them, the wing to front panel seam/wing to scuttle seam, will always move. If you fill the gaps with filler then it will crack as the body filler isn't flexible.
To fill the gaps use flexible seam sealer(not silcon sealent!!).
I would assume an acrylic seam sealer would suffice?