It seems like you might be putting a little too much time into making the truck neat at the cost of ensuring accurate loads (I did the same thing at first). As long as you have the loads on the correct shelf in relative order, the driver is going to find it. I would suggest putting a bit more time into ensuring accurate loads and not worry as much about how good the truck looks. The driver organizes the truck as he/she makes deliveries throughout the day, so putting too much time into a really good looking load is a waste of time for you. Slow down and get your misloads under control and then focus for the superb standard of neatness. Furthermore, if you feel you've had to make a significant compromise in organization, just give the driver a concise rundown of any irregularities in load. Communication with your driver (whether face to face or through marking the boxes) can go a long way for less than ideal looking loads.
If it makes you feel better, when I first started loading I had like 33 misloads at first. And if that's not bad enough, the full time sup told me they were going to keep me there because I was relatively accurate and had neat/sturdy loads compared to other guys in the building. Yeah... However, over time I eventually got to the point where I didn't have misloads anymore. Months later I ended up driver helping for the driver who had my 33 misloads, when he confirmed the pen number he was parked at, I realized it was the truck I loaded. I told him it was me and that I was new to the position at the time and apologized. He was cool about it (probably since he had a few months to cool off) and told me he respected me owning up to it. So just take it one box at a time and try not to get overwhelmed. It sounds like you're a good employee with a good attitude so just keep trying to do better, most sups will recognize that even if they chew you out.