I was looking to use a sled, because the gym has been packed with people. More standing around than work going on.
The sled seems to be a good choice for the next 4 weeks.
I would try both. Believe me I know what a gym packed with people is like. But once you can jump in and grab a rack, it's yours. Also consider going during a less crowded time. Remember the most effective training is usually not the most convenient.