I'd give Robert Ten Eyck's idea a try too.

The hull bottom is a good place to find out how the filler looks. You won't see it later.

NOW is the time to go over the hull carefully and find any mis-aligned strip edges. It's easy to fix them now.

Cut on the strip joint with a new utility knife blade, apply glue and force the strips into alignment. Put scrap strips across with hot glue to hold the hull strips in place until the glue cures. 1/16" thick scrap strips will conform to curved surfaces.

I started re-aligning the strips as you describe - waiting for the glue to cure, but seems to be working.

I appreciate all the suggestions on fillers. I picked up some Durham's, and I just glued up some strips with some flaws so I can do some testing. I'm going to consider this carefully - in some cases might be best to just leave it alone, as the repair might be more noticeable than the flaw.

Of course, now that it's too late I figured out what I must have been doing wrong to create those "heel/toe gaps" in the first place, and that it would have been pretty easy to identify and fix them BEFORE gluing in the next strip, using a straightedge as a reference. Oh well - next time.