*sigh* This humping thing

Zibi was a solo puppy and is rather socially inept.  He doesn't know how to play. He seems to think of just one thing to do at the dog park with another dog his size -- check it out for hump-ability and then proceed to obsessively follow and hump.  Dogs are amazingly tolerant or oblivious of this.  He sometimes decides not to mess with a dog, but once he has decided to give it a shot, his focus is intense and to the exclusion of everything else (read: me). 
 
Yesterday it was an dachshund, Maltese, Shih tzu cross .(imagine this ... ST body with shorter legs and a really really long pointy nose and terrier tenacity) ... happy fast dog, taking balls from the big dogs, offering to play with Zibi .. first time I've seen a dog offer up bitey face and wrestling with Zib, who is completely clueless. 
 
When the humping starts, he will not stop.  Generally I wait a bit to see if the other dog will tell him off.  Which so far hasn't happened. So I pick him up or put the leash on him and diverge from the path of the humpable dog.  Yesterday the owner didn't care, the dog was funny and fast and keeping Zib moving, so I just waited to see if he would ever give it up. He did not.  He had an erection and when the other dog pulled away from he, he'd air hump and seem confused.
 
When the old dog Coco was with us, he never tried this.  She beat him up daily for any infraction so he wouldn't have dared.  I sometimes ponder getting another dog, but if I had to live with this all day every day it would be impossible.
 
Zibi generally ignores all big dogs at the dog park and barks reactively to all big dogs on our land (we live on 30 acres where people from the neighborhood walk their dogs, most often off leash.). He really perks up when he sees a little one and I'm always hoping for a friends.  But then the humping starts, does not stop and it is a huge drag. 
 
It seems like his world is getting smaller and smaller.  I have to keep him away from kids, which means 90 percent of our community, he's recently started being grumpy with adults so they are advised to ignore him, he either ignores or is dangerously assertive to big dogs and now he can't even be around little dogs.  It makes me sad.