Christmas Tree Siphon.
Cost: not much
1-gallon jug
rubber stopper with two holes
8-feet approx of flexible clear vinyl tubing
2 lead sinkers
any old funnel
Mark the jug with a MAX line equal in height off the floor to the MAX water level in the treestand. Weight each end of a long tube (long enough to reach from the treestand to several feet away from the treeskirt, say) and sink one end in the stand and the other (thru the stopper) in the jug. Add water into the jug up to the MAX line (or more on the initial fill only). Stop the jug and blow into the air tube, forcing water to the treestand. When siphoning begins you're done.
Use a funnel to keep the water level in the jug at/near the MAX line. No more bending under trees; no more reaching thru branches to a funnel; no more sticking your finger in the treestand to see how much water it needs.