There is no need to bend significantly, be on your knees, and there should be minimal pushing involved when using an alaskan mill. If these were essential I would never have become involved with alaskan milling. Any log that can be place onto a WWM can be lifted off the ground using jacks and onto gluts or strong sawhorses, to a standing working height. Using natural or artificial slopes make it easier still and with short logs where steeper sawing slopes are practical there can be near zero pushing involved. Sure by the time one adds up the weight of sawhorses, rails and a jack we're approaching the 100 lb mark, but all this allows the operator to mill on relatively steep slopes, and tackle irregular shaped and/or really big logs. The alaskan design with the addition of a few simple techniques and jigs (like plastic skids and inboard adjustable wheels) continue to make it the most versatile portable mill around, certainly for breaking up logs.
I cycle around about a dozen designs of unfixed and fixed small scale sawmill configurations in my head (single/double/multiple beam,vertical/horizontal/sloped, fixed to log/ground, and some outside the square over/under designs) and have notebooks with many ideas sketched and scribbled out in them. No matter which way I look at at it, for what I like to do I always seem to come back to the basic alaskan. Of course, as they say, "your mileage may vary", and if I did this for a living, design sacrifices would have to be made to increase productivity.
