"Also, what if you want to travel light? I only take a backpack and it is already packed full."
Granted, the GPS is pretty small and light. But there's also the charger or cigarette lighter plug to take, and maybe a suction cup mount to mount it to the car windshield.
If you don't want to take your own, you're stuck with getting one over there, which usually works but sometimes they don't have it for you like you'd requested...see post above.
I assume you'll have a car, so once you get there you don't have to put it in your pack any more. Leave it hidden in the car.
If you're talking about using it only in pedestrian mode, be aware that at standard walking speed most GPS units can't get a satellite lock when you're in towns on narrow streets where the buildings around you block the signal.