Can't help you much on the weight side of any yaks as most are in the 50-60+ lbs range. While surfing the net I came across this innovation for a truck rack. Check out the 7th post on this link (One with blue truck in pics).
http://yakass.net/forum/yakkity-yak/...anagement-mods The rear lift can fold down so you "roll" your yak up or down on the rollers that are installed. Granted that this would only work if you
do not have a shell on the rear, but worth looking at for some other type of modifications.