I have an idea but you may not like it. Place a back seat on one of your tractors and have your grand son hold the weed trimmer while in the seat. You drive the tractor slowly and he runs the weed trimmer while on the back seat. That way you both are sitting down without walking the distance.Well all, even as I am retired I am finding it hard to find time to mow the grass. Neighbor cut his yard today and it was driving me nuts as I couldn't start mine as I was waiting on a call from the car dealer that was checking on an issue with my wife's car. They finally called at 4:30 and said they were still investigating the issue. By then it was 95* with a heat index of 105 so no weed whacking. Tomorrow morning I would like to weed whack, but I have to go to the vet with my wife for dog meds and fill the truck up. Depending on what the car dealer finds, I may try to get the trimming done when we get back from the vet, and mow Saturday. Still sorting out how to make mowing easier with the new equipment.
The Poulon weed wacker will be a quick use getting into the corners and what not, still a lot of walking.
The Murray wheel trimmer will do the majority of the edging, but will be covering the same ground as I did with the Poulon weed wacker.
RED will take care under the trees.
And BOH and the tow behind will do the rest. Still figuring out the angles to prevent un-cut strips
Sort of a toss up on is it any faster using more machines, or does the extra maintenance and clean up off set the time mowing. Seems the walking distance will be more as I have to use the little trimmer to get areas the big trimmer can't. Next couple days will tell.