Get yourself some orange lipstick, make sure it doen't have glitter in.
Cover your 5 O'clock shadow with the lipstick & wait a while for it to dry, then apply your foundation on top & hey presto your shadow will be much harder to see. You may need to experiment with how much to use & what shade, personaly I find a darker orange works.
Red lipstick also works if you're desperate but you may look slightly pink if you're not carefull.
A bit of powder on top of the foundation may also help but a friend warned me that powder can often look false, she also pointedout that if you're not carefull putting powder on then you may accidentaly remove some foundation.
The reason this trick works is something to do with orange being opposite in the colour spectrum to the bluish/black of stubble so cancels it out.
I'm sure there are others who can explain this better on this forum.
Also, I recently bought a Phillips electric shaver (I can't wet shave), it uses the lift & cut system & give a very close shave, it certainly helps & i'm glad about that because it was pricey
I hope this is of some assistance
All the best
Jayne