I can think of two options. You can tell the hotels/motels where you will be staying about your child, and they will be sure there is a plastic sheet over the mattress if necessary. Or, you can take your own supply of diapers, bed pads, etc. with you. I have done both, and find that notifying the hotel is usually the better option. Most hotels and motels are aware that many guests are bedwetters, and are used to dealing with sleepwetters.