: I think I'm going to use some wood filler to fill in some gaps on my stripper
: prior to sanding/epoxy.

Sand it first. You don't need to get down to your finest grit, but as you fair the hull some of those areas you think of as gaps are going to shrink in size, while others may appear to expand. Save some of the sanding dust.

Once the wood is sanded, you may find that what you perceive as gaps now, will simply be seam lines, which you are not going to fill, or sand out. You just live with them.

You can use the sanding dust with epoxy as a filler. Put it in, wait until it has set up, but is still soft ("green") and use a cabinet scraper to remove anything that is out of place. Let it harden completely and do your next finer sanding stage.

In his book on strip building canoes, Gil Gilpatrick suggests filling the gaps while doing the initial seal coat of epoxy. After covering the wood with a skim coat, ome of the epoxy resin left in your mixing pot is going to gel on you, and as it thickens it can be used to fill gaps. Once it starts to gel it won't run out. It should still be possible to mix in some of your sanding dust.

PGJ