I don't get it. Forty pounds over 100 yards? Pack the weights into two nylon mesh shopping bags, you could use dive bags if you are made of money, pick one up in your right hand , one in the left, walk. When you get there have a beer. The mesh bags are light, compact when unloaded, and allow you to see what is inside and hose off the weights without having to unload them.

Average weight of concrete blocks is about 44 pounds and we used to carry two at a time, one in each hand, all the time. If we were feeling strong and shorter distance, and had our Wheaties, four at a time.

Some dive shops running trips use milk crates for dive weights and similar heavy and bulky gear. These they stack and move down the dock with a simple hand truck.

If terrain stops wheels then you might rig a simple pole and suspend the bags or crates from each end. This is very popular in Asian nations. Traditional European farmers who use a functionally similar but more elaborate carved yoke. Using this they move hundreds of pounds for miles. Forty pound would be trivial.

Forty pounds is light enough that you could put the weight in a simple bag and tie on a piece of webbing sized to go over the top of the head. The webbing rides on top of the head and the weight hangs behind your back. You can add a line around the waist to keep it from swinging if it seems necessary.