Solution
Unfortunately the SteelHead does not reflect the DSCP marking from the inner IP header of the TCP connection to the outer IP header of the UDP channel
If the deployment in question has Internet traffic backhauled from a Branch SteelHead to a Datacenter SteelHead (DC) then QOS markings can be applied or reflected on traffic between the Branch to DC. In that mode traffic between the Branch and DC is not UDP encapsulated yet so QOS marking will work as usual.
If the deployment in question is for a SteelHead with a direct to Internet link and QOS marking needs to be applied or reflected, then an external device (such as a router for example) must do the DSCP marking and prioritization for all of the UDP 9545 traffic as desired