Looks like you need some snow on the ground to get that sled going! Did you ever see the video Taffy posted a couple years ago of her friend's kids racing across a snowy field in a sled pulled by their dairy doe? It was hilarious! If you never saw it I'll have to dig it up. They were flying!
I don't think you need to worry about screwing up your goats. You are a very conscientious goat owner and you pay attention! If one of your guys starts to get sore, you'll notice it. Some owners wouldn't. If one of your guys starts to balk, you'll try to figure out what's wrong with the equipment instead of immediately blaming it on poor attitude. I've heard over and over that Nubian goats are lazy and stubborn, but as I've learned more about goats and goat saddles, I've come to realize that wooden goat saddles DO NOT fit most Nubians. I think of the purebred Nubian bucks I had, and while they did indeed have very easy-going personalities, I would never classify them as "lazy" or "stubborn". In fact, they were huge people-pleasers and would try things for you just to make you happy, even if it wasn't something they would ordinarily be adventuresome or athletic enough to try on their own initiative.
I think of my guy Sputnik. He is 5/8 Nubian and has a lot more of the Nubian-type personality traits than our other crosses, including the tendencies to be loud, timid, and lazy. He's nothing like the bold, athletic Finn who likes to show off and perform crazy stunts just for the heck of it. Sputnik is cautious on steep terrain and near cliffs, and he's never sure whether he can jump into the truck and often needs a lot of encouragement to try (and he always seems surprised with himself when he makes it). Sputnik gave me some major problems on the trail one time when I tried to remove something from his panniers. He leaped up and almost knocked my front teeth out with the wooden crossbuck. He had also been lagging and complaining like he wanted to go back. It turned out that the wooden saddle didn't fit him at all and he was telling me he was in pain in the only way he knew how. I switched him to the Sopris saddle after that and we never had another problem. In fact, he loves to be saddled and acts disappointed if I saddle Finn instead. He grew out of the loudness, and the only time he ever woke us up at night was at Rendy 2017 when he started bawling at the top of his lungs at 1:00 a.m. I couldn't figure it out until I smelled smoke. I checked our campfire and someone had thrown some paper plates into the ashes where they had eventually begun to smolder. As soon as I took care of it, Sputnik quit hollering. So sometimes that noisy Nubian trait comes in handy.
I often wonder if Nubians have been unfairly judged simply because we did not understand them.
Sorry for the off-topic rant, but it's my very roundabout way of saying "You got this!"