I think training on your skis is the best thing for you if you are a skimo racer and have easy access to snow. One long hard Z2-3 workout every 2 weeks is not a bad thing. I would be sure there is enough Z1-2 training in these weeks as well as some Z4 workouts since you are close to racing season. If you have are racing regularly (like every weekend) then drop the Z4. If you are also just beginning your ME training and also trying to race at the same time you must expect that your race performance will not be the best.