Try a pair of the lycra warm up shorts or bicycle type shorts (without the chamois pad of course). They are generally nearly knee length and stay tight to the skin so will not let the cold blows reach the nether regions. Then you will only have about 6 inches of expeosed knees between your hosetops and the bottom of your shorts. Betweenyour shorts and your military weight kilt you should be fine, as your knees can tolerate being a bit chilled for a long time (much better than say ears, face, hands or feet).