LOl. 20 sites isn't a small number unless plan on creating some sites that you don't really care about, at least thats how I feel.
Having 2 sites with thousands of pages is easier. SEO would be much easier as well as you start to deep link. I wouldnt be doing 20 sites.
As long as the clicks are legitimate, you don't have to worry. Also with bigger sites, google gets lenient. I mean if you are getting 100k uniques per month than few clicks here and than won't matter. Google don't count such clicks. Best of Luck anyway. Please keep us updated on your progress