Just in case you are not already aware, you must take the time with
picks/scribes/little looooooong screwdriver and clean the heads of the CV
bolts. Dirty job. first knock of the big chunks with a wire brush, then dig
out the heads inside and outside, then spray with PB Blaster, then clean
the insides again. If you just jam the tool into those dirty heads, you
will wear out the tool before you finish and strip a bolt. It takes more
time to clean the bolts than it does to remove them.

So why not as standard procedure, when you put back new or cleaned bolts,
pack some 1950's type high fibre wheel bearing grease in the heads. Bosch
dizzy cam grease is similar.  They would still build up crud all around,
but once you knocked off the chunks, they would be easy to clean the inside
of grease and no debris. Simple idea and wouldn't surprise me if it is in
the archives somewhere.