hi - i was raised predominantly by my mum... my parents divorced when i was 8 and my father passed away when i was 9. my mum as never v positive about my dad which made me very upset, especially when i got older, as he is v much a part of me even though he was not there in my life from age 9...so i think it is fantastic that you are positive about Cooper's Dad. I also had a lot of contact with my Dad's family thru my life which I treasured and my mum made sure of this as did my Dad's family.
Anyway in terms of male influences i do think this is important. Probably even more so for a young boy. I spent a heap of time with my uncle and my older male cousins and I had various family friends who took on a bit of a 'fathering' role to me. I loved this and felt like i was a v special part of their lives and my mum encouraged it a lot. So try to reach out to other men in your life who can have a special bond with your son...
HTH and good luck, I think your attitude is wonderful