When using any kind of fatty meat it is crucial that the fat is rendered properly. This is what makes the fat melt in your mouth, not chewy, tough, and disgusting. Visually you are generally looking for the color of the fat to change. My rule of thumb is rendered = yellow/translucent and unrendered = white/opaque. You do this by cooking the fat long enough at a low temperature so the fat can change. Outside of bacon, not rendering fat is how you royally fuck up a great steak.
The best advise I can offer is to just render your bacon first. For instructions on this see
this website. Then use the bacon drippings as seasoning in your beans, not that actual chunks of bacon. Store your bacon bits to use as a topping for the beans once they're done. This is my preference because I like the texture/crispness of cooked bacon to be preserved as best as possible. The once your beans are ready, do not re-heat the bacon before adding them your beans, let the heat from the beans do that, otherwise you'll risk burning your precious little chunks.
Sorry this is in a totally different direction that you went this time, but I'm very particular about bacon.