Since every leg is a little different and the tail section isn't perfectly symmetrical, I have to basically custom fit each leg to its section of the fuselage

So I'm just using a tiny piece of sandpaper and the tip of my finger. Making them out of softwood is coming in handy, as removing material is pretty easy.

I also found that rubbing the leg up and down while applying pressure makes slightly shiny spots that I can then sand.

It's a laborious but effective process

Use a piece of sandpaper (paper side against it, abrasive out) on the piece you’re trying to mate to, and it’ll sand in the same profile.

You should use a dowel instead of your finger since it doesn’t deform too much as well. Basically you should use a sanding backing block, in the same profile of what you’re trying to sand it too. Flat block for a flat area, dowels for round, stuff like that.

Do your best and caulk the rest!

The sandpaper isn't flexible enough for that, it doesn't like to curve in two directions at once

I've accepted that I'm not going to get it PERFECT. As long as the gaps are less than, like, 1/16 or 1/32 and can be arranged to be at the bottom where the leg will cover them, that's fine

I was mostly being facetious. Clearly you are determined to achieve a higher level of quality. I wish you the best.

Gap fill with wood glue mixed with sawdust. This will be sandable/stainable/paintable.

Spoken like a true caulkender!

I thought you were making a wooden Enterprise and this was the neck connecting to the secondary hull. My disappointment is immeasurable. 😆

Is this the toy rocket posted about earlier?

Yep

Never let perfection stand in the way of good.

I did too.

That is the major struggle right now. I forced myself to accept them as-is and move onto gluing

Looks good enough to me and besides, you may decide to paint it with some paint that applies a relatively thick coat, which would end up filling those tiny gaps anyway.
Anywho, keep going good work!

This project is so stupidly engaging.

Keep with the updates, I love to see them.

You can soak sandpaper in warm water to make it more pliable.
I recommend trying out out with a small piece first, to get an estimate on how it holds up.