I wouldn't do it. None of the positive options you are suggesting ("financial security, a great small town for our child to start pre-kindergarten, and a security with family and friends") override the importance of your husband being there whenever possible and being together as a family. If anything, I'd try to find a place to live closer to where your husband works so that you can get him home more...and hopefully, given more time, you can find a job for you!
There's so many potential issues that could arise if you don't live in the same house. You're almost for sure going to grow even further apart than you might already be (considering he's working a ton, I could see it might potentially feel like you aren't as close as you want to be).
If it's hard to decide, maybe try putting yourself in his shoes and see if it makes more sense why he's quite opposed at times. Would you feel okay with your hubby living somewhere else with your son, causing you to see them less? Even if you were already working a ton, every little bit you did get to see him/hubby would be important to you. So, if your hubby came up with an idea (moving too far away and taking son with him) and only make it so you see them only a few times a week...probably wouldn't be too appealing to you. I know I would be completely opposed to my husband moving away from me for a job.
I wouldn't do it, if it were me. Honestly, I'd stop considering it completely UNLESS there is a way to move as a family. I think that should be the top priority.