I use this lock on my service truck. My truck has a whiting roll up door. There is also a model for Todco doors so you would need to know what door is on your truck. Installation requires you to drill 2 holes. If this is a rental truck that could be problematic, but if you removed the lock and hardware and returned the truck I doubt the rental check in inspection would notice the small holes. Especially if you touched up the paint.
As for security, its just like any 6 pin paclock and the position of the keyway against the door would make it very impractical to pick. Cutting without power tools is also unlikely. The only exploit I can see being quick and practical would be heating up the metal support bracket cherry red with a torch to soften the steal and bending the lock out of the way.
We've got a lock just for that! We call it our TL84A and there are 2 style hasps that work with either Todco or Whiting handles. The shape of the lock is pretty unique and I think it's one of u/PAC_PREZ's favorite locks we make. Looks like a puck, but with a leg on the bottom to block the hook from coming up. Check it out here and let us know if you've got any questions!