Opinions on keeping horses on property?

Well you seem to at least have some common sense. Do talk more with your instructor and anybody else you know that has good horse knowledge. Do you already have a vet sut up? If not, at least sign up with someone and get an idea of what it'll cost for a simple visit and beyond. They should be able to help you with what and how much to feed your horses. You'll also need a farrier if only for simple trimming, though with help you can learn how to do this properly on your own, but only trim on your own after you've had a lot of training. The horses will need somewhere to get out of the mud, if this is a problem, and it can be as their hooves tear up ground quickly. Do your research about costs to see if you can afford not only the move but the property taxes plus basic care and any emergency fees that might arise. It seems like you know how to go about most of this, but you can never ask too many questions. At this point, just ask around to as many people as you can think of as many questions as you can come up with.