Layering your garments is the way, you have to be conscious of your body temp - absolutely no sweating and stay on the cool side rather than the comfortable warm.   side.  You have to be monitoring your body temp so that you dont build up moisture in your clothing.  When you take off a piece put on your pack so that it dries out and have dried out clothing available.  I use polar fleece rather than wool.  It dries out faster and provides the same warmth as wool.  i have worked out in -45 weather and do it all day.  I dont go into a warm place with my outdoor clothing on I take it off outdoors.  If I do that I would not be able to go out all day.  You should have at least 3 or 4 layers that you can remove and put on when needed.  Keeping in mind that the pieces you take off you have to dry out.  I was a field service mechanic and would work out side all day and go into a warm place until the end of the day.  I never used insulated coveralls- too expensive and hard to clean the grease and oils that I dealt with.