Ask a Business Lawyer. Get Business Law Questions Answered ASAP.
Please note: (1) this is general information only, not legal advice; and (2) I will provide you with honest information and not necessarily to tell you might be hoping to hear.
Sorry you are dealing with this situation. Unfortunately, you may not place a lock or boot his RV even if he has not paid rent. The laws require you to give a 72 hour written notice for non-payment of rent and advise the tenant they have 72 to remove their RV. If after the 72 hour period is over you can have the RV towed. Here is a link to a sample letter: www.wiki.answers.com/Q/What_are_Texas_RV_park_occupancy_laws_for_evicting_a_person_and_their_RV_when_there_is_not_a_rental_agreement
If rent and other fees are still owed and not paid to you on demand you would need to take the tenant to small claims to recover.
I apologize that this was probably not the answer you were hoping to receive. However, it would be unfair to you and unprofessional of me were I to provide you with anything less than truthful and honest information. All my best & encouragement. Please note that you are asked to rate my courtesy and professionalism, and not whether the answer supports your legal position. I only receive credit when rated 3 or higher. If for any reason you feel that a low rating is appropriate, please first give me the opportunity to address your concerns by clicking the "reply" tab. All states have intricacies in their laws and any information given is simply information only and specifically is not intended to be, nor does it constitute, legal advice. This communication does not establish an attorney-client relationship with you.