There are more than 50 reasonably priced RV parks in the Mission area alone. Come down and pick a park and stay a week. Drive around and take a look at the others. Mission West even has a low cost Passport America rate for a few days.
Here is how I rate them:
Bentson Palm Village - May need a reservation
Green Gate Grove (Lots rented by owners)
In no particular order
Seven Oaks - Big sites, nice pool, sand burrs
Mission West – South edge of city and a little rural but some real nice concrete sites.
Bentson Grove RV Park
Canyon Lake – North of town, rural feel.
Bentson Palm RV Park - Not to be confused with Bentson Palm Village
Sleepy Valley - Older but has some shade trees
Mission Bell has very small sites, busy park with lots going on.
Pleasant Valley – Lots of concrete, very clean, many Canada guests
Take a look at www.rvparkreviews.com for more details.