I, too, am single with a young child. I do not expose him to any men that I am dating, period. He spends plenty of time with me and a few good male friends - and they are "uncles" because I see them as lifetime friends.
All I can say is BABYSITTERS - plain and simple. Talk on the phone after bedtime, etc. You'll find that you will only go out a few times a month and even then you'll really have to consider the person "worth it"
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Good luck - it really is possible.