No, you cannot just park wherever you are for the night. Many jurisdictions have laws against overnight camping in their public facilities as well as in store parking lots and even on the streets. Additionally, many places that are easily accessible with even a small trailer are not particularly safe at night. There are many low cost or even free campsites, and a previous poster listed some links. Passport America, a camping club that gives 50% discount on camp fees is another resource. Harvest Hosts is a club that gives free camping at wineries and farms.
