Nothing wrong with a 10' surf rod at all.
Just my opinion (not cast in stone) anything over 3 oz I'd prefer conventional gear. Actually 2oz+, I like conv. anyways.
Your spinning rod could be a bit heavy for plugging (maybe). but you're not listing what the rod is designed to handle. "4 oz plus bait" leads me to believe it's in the 6 oz. range.
For spin I'd probably look for 3/4 to 3 or maybe 1 1/2-4,or there abouts. It'll cast better for you if you match it up.
With plugs you'll be doing a lot more casting. A better matched rod will let your shoulder and back live longer.
Most of my plugs are tins / leads in the 2-4 1/2 range lately.
Everyone is different. What works for me, may not for you.
I don't think I'd be concerned with OTG for plugging with a spinner,,, but maybe.