Hi Connie and thanks for your very interesting question about deer fencing and mason bees. The problem with mason bees is that they don't fly as far as honey bees to find their pollination sites. If you put up a mason bee house and some new larvae inside the fenced area, you will have better luck than if you expect the bees to work their way through holes from any distance away. 

Honey bees will fly over a mile to find flowers while mason bees keep closer to 300 feet from their nesting site. It too have a farm with berries and fruit trees and we place nesting boxes at several sites around the yard along with water/mud baths for them to plug their holes up. They do a fantastic job of pollination (2 mason bees do what 50 honeybees are needed for) but also have some parasites, so be sure to clean out the tubes or houses each winter and put the clean larvae in the refrigerator until the next spring.

Here is everything you could ever want to know about the fuzzy little darlings:
https://extension.oregonstate.edu/catalog/pub/em-9130-nurturing-mason-bees-your-backyard-western-oregon
Thanks for asking,