Same here.

I would probably slide the stabilizer so it is about a glue-joint-width from being in place (i.e. most of the way).
Then apply a bit of slow-setting CA right along the joint, push the stab through so it's the same distance out on the other side, and apply another line of glue.
Finally center the stab in the fuselage (maybe even move back and forth a few times to get the glue spread out inside the joint) and let the glue set.

My bad. I thought the stab slotted in from the side...
I see from the manual it slots in from the rear (sorry, I can't post an image or link...)

Same basic suggestion. The idea is to get glue onto the stab and then distribute it between the two (hidden) surfaces.
In this case I would probably try to get glue inside the fuselage slot using a hypodermic needle or just carrying small bits from the glue dispenser tip into the slot on the end of a bit of solid wire. Then push the stab in place and align it.
Alternatively, you could try a modification of my first suggestion and slide the stab in dry, then slide it slightly to one side, apply glue, slide it to the other side, apply glue, and then put it in position.

A thin epoxy (like WEST System) would also work. You can clean excess off before it cures with denatured alcohol, if you get a little too much in and some of it oozes out.

If you're concerned about the joint's strength after that, you could apply a small fillet of CA or epoxy between the stab and fuselage-sides after the first glue has cured.