Sliced smoked shanks are the best, but another possibility is a spicy pancetta, an Italian bacon like thing. You can try it in a skillet before adding it to the soup. At the end it will have lost all its flavor but the soup will be amazing. Of course if you are making it in a slow cooker, you may wish a one dish easy meal and trying the pancetta is extra work. Also finding the spicy pancetta is not so easy.

You won't lose flavor, but it will definitely be a different flavor!

One more suggestion . . . a generous spoonful of crème fraiche or sour cream added to each bowl of split pea soup will transform it. ;o)

I love pea or bean soup and make it with whatever kind of pork I have on hand--the bone left over from a country ham, ham hocks, slab bacon, sliced bacon, salt pork, canned ham, smoked butt. I use bacon for soup made with fresh peas because I don't want the peas to be overwhelmed by smoke or salt, and I do it the way AntoniaJames suggests above.

You will definitely lose some flavor, because the ham hock is a joint, and is smoked/cured, and will be much larger than the amount of bacon you would add. There is so much flavor in that bone. It's worth finding one, or better yet, a smoked ham shank (larger, more meat). If you do go with the bacon, you should (i) cook it until crisp in a pan to bring out the flavor, as you can only do at the higher high heat in a pan; and (ii) saute your onions in the bacon fat, and then scrape up all of the bacon bits into the crock pot. Cooking the bacon itself in the crock pot will make it somewhat unappealing, at least to some people, as it will lose its crispy texture, becoming soft and mushy. I might add one or two whole pieces (cooked) for the flavor, and then chop and add as garnish the crisp, pan-fried bacon. I'd use a rich chicken broth, too, in making the soup. (I make split pea soup often . . . .had it last night, in fact!!)

I'm not sure about bacon. My mother, who was Jewish and wouldn't have pork in her home, substituted 'flanken' or short ribs. I'm an atheist and keep everything in my home, but I continue to cook split pea soup using my mom's method. It's delicious. Keeping with my childhood roots, I save some of the flanken and eat it smothered with ketchup, very unusual for me. Fir kids, it's also tasty with some sliced hot dogs. I haven't tried it this way in 30 years, however.