Hi,
I'm from Texas, but I don't think I am one of the sages. I have had a brush or two with the sages on this site, so I think I am a "Sage Brush." I have not heard of that particular park, but if they have an ad in Trailer Life, but no review, that means they are a new park. Mission is in the Rio Grande Valley, referred to as "The Valley" in Texas, a very popular area for Winter Texans (the PC term for Snowbirds). March and April is the time that most of the Winter residents begin to leave the valley for their yearly migration back North, and some of the Parks close for the Summer or at least have seasonally reduced rates.
In March and April, the Texas Hill Country, which extends in an arc from about 100 miles WNW of San Antonio to just West of the Austin area, has some beautiful RV Parks with great scenery, beautiful weather, and crystal clear spring fed rivers. I will not recommend a particular park, that is for the true Sages. Wherever you decide to visit, I hope you will enjoy some great Texas hospitality.
Doug