My answer may sound like a joke, but let's go anyways:
Travelling trough sand is incredibly hard. After all, it's all glass broken in very, very little pieces. Unless there is a very good reason to dig trough it all the way (other than "avoiding orbit detection"), I would recommend the cheapest, easiest way to go:
Give your crew 30 sand-bycicles (and a camo suit).
The trails left behind the bikes will be almost invisible from orbit, if not totally covered by small winds in minutes. And because they are very small (and sand-colored), the members of the crew would be nearly unnoticeable on such a large surface, on the contrary of a ship that would remove tons of sand and leave a giant trail visible from space.
50 miles a day by bike may be a lot if the crew is not trained however. On a flat surface, riding a bike 45 miles is about the same in energy requirement as running 5 miles or so. Sand dunes being made of... well, sand, I guess it would take some training to ride the same distance within a day, so it's not a trek for everybody.
Also I assume the purpose of the ship is not just for the crew, but for good and supplies too. Each bike can have dual bags on each wheel, up to 30 liters capacity by bag. That's already 60 to 120 liters of gear by person (depending of their respective weight and training). That can go up to 3600 liters of goods for the whole crew. And I'm not even talking about bycicle trailers...