Hmmm... I agree with an earlier poster that we as scouter should not expect troops or packs to purchase and maintain equipment for other packs to tear up, without the clear expectation of a sharing of the costs.
With that in mind, you don't have to couch the recompense as a fee or rent, but as an expected donation to cover the cost of wear, tear, storage, and upkeep.
If there's risk of damage or loss, seems to me the Pack 'borrowing' the track should request a representative from the 'loaning' Pack to help set up, tear down, and return. Also, a brief contract might be in order stating that if the track is damaged, the borrower should cover costs of repair. At time of 'teardown', track should be examined by an authoritative and responsible member of BOTH Packs, to ensure no damage has occurred, and that all parts were there and operating, before disassembly. The contract ought to be signed by both parties stating the track is ok and no parts are lost.
Shame that even in scouting you run the risk of people taking advantage of you, but it's certainly possible. Our Cubmaster went through considerable expense to get an aluminum track for our Pack, and I'm sure he wouldn't want it loaned out and damaged, to be repaired at his expense.
This plan actually DOES put an undue burden on the loaning Pack to always have a rep present, so some donation to cover their time, gas, and food, would not be out of order, and does not constitute 'running a business for profit.'