Got the transom fully installed tonight and 'glassed into the bottom of the hull.  I mixed some resin with filler and made "fillets" or blobs of thick epoxy that stay in place (vs. run like the non-thickened stuff).  That allows the fiberglass mat to turn the corner easier with less (or preferably no) air space between it and the surface you're sticking it to.  I ran fillets up about 1/2 way along the sides.  Any more than that and I'd need a couple pounds of the stuff and if you've ever paid for West Systems epoxy, you know why I'm not going to do that.  Take a look at the Installing the New Transom page for more.