I agree with Ross. You can make the fillet really tiny (1/16") and that will be enough to help the bias strip stay against the seam. Also, after the fillet is cured and you are ready to lay the bias strip on, you can paint epoxy on the joint and lay the fabric into the wet epoxy (instead of vice versa); that tends to help the fabric "suck" against the irregular shape. Consider buying a small batch of fast hardener - it develops tack quicker and will help keep the fabric in place.

I hope this helps,
- Chip
http://www.nwlink.com/~chips