Eric Lambi writes:

If you screw up gluing your tires on and get a bunch of glue on your
tire sidewalls, is there any easy way to get this off?

Your rim glue should be dry by the time you install the tire so it
shouldn't "get all over the place". Road glues are tacky when dry and
are designed to accept a spare tire on the road if you get a flat.

If you don't believe the tire is on securely enough, you can try to
lift it off after riding a mile or so. Just braking on a short
descent heats the rim enough to make rim glue re-flow anyway.

Also, I have this habitual problem where I end up really struggling
to get the last section of the tire over the rim (this is what
causes the mess). I stretch the tires before I put them on. How
can I prevent this problem?

Did you previously mount the tire on a clean rim and inflate hard?
That is a way of easing that first stretch. Just the same, the bias
ply of the tire casing causes it to constrict on the rim when
inflated. Initial tightness on installation is not an indication of a
tire that may or may not stay on the rim better in use. Inflation
constriction is the main holding force, rim glue reduces tire creep
and is mainly a backup retention in a crash.

You'll notice that the tire will creep forward on hard descending from
melting rim glue and braking traction. This is apparent because the
valve stem will be angled, something that can be corrected on the
front wheel by reversing it.