I live in the Wellington area and my daughter rides near all the show grounds, therefore I see and feel the activity. The Equestrian area here has been very consistent and easy to rent. Last year I had a listing that was a 3/2/2 pool home in a gated community with 1,700 a/c sq. ft (It was 2 miles from the Show Grounds) and it rented for $4,500 a month (January -April). This was without a barn facility. It is something to consider especially with the deals you could get on building the barn etc.. Feel free to visit my website and click on the equestrian link. It has a few links on show etc. It will be a good source of information for you.
Feel free to e-mail or call if you have any further questions and good luck!
Keller Williams Realty
I am posting here a link with ALL activity in this area, Little Raches East, for the past 6 months.
Take a look and let me know if I can help you in any way.