R.I. Gen. Laws § 44-19-3: Temporary permits.

The tax administrator may grant a temporary permit to any person desiring to engage for a limited period in the conduct of a business as a retailer within the state, or to an itinerant merchant, seasonal retailer, peddler, or person selling tangible personal property at retail without a permanent or fixed place of business within the state, under any rules and regulations that the tax administrator may prescribe. A retailer who has no regular place of doing business may be required by the tax administrator to attach the permit to his or her cart, stand, truck, or other merchandising device.