Hi Joachim 

I did a code for that. 
First thing i create a route for pending. All orders coming on odoo are with this route on the begining.

Then , i have a job which runs every 10 min which get the stock and decide which "real" route is the best for me.  

Then , I assign it on the each order line and  i cancel the pending picking.  (be careful  you have to remove the warehouse selected on the order else it will not work)

At the end , for each line contains product of the order i call this method _action_procurement_create() 

It works since more than 9 months now . And we are totally flexible with this system .

We had a route management on the product (a master warehouse if stock on multi warehouse) , we had also route for no stock , anomaly (bad address for example) ....

I hope it s understandable  :) 

Good luck 

Hi Thomas,

I'm having the same issue. Did you figure it out?