I would personally suggest breeding your standardbred mare, it would be less potential stress for the mare ;)
(Small mommy, fast growing baby could have trouble bending down to nurse at 5 months)
So long as your standardbred mare is well taken care of nutritionally, she shouldn't have any problems with a fifth foal.
Is there a cross that would allow the foal to be registered? Do you have potential stallions in mind? What kind of conformation do they have? What about temperament?
Good luck in your search, too bad you can't just import a potential training candidate for cheap. The problem I have personally found with inexpensive young horses/ponies for sale is that they tend to come with baggage. Usually a reason why they are for sale that the seller isn't completely honest about, whether it is their temperament, conformation, habits, or some other reason (like a problem with getting them registered, something that happened to my mom when she was handed the registration papers on a long yearling out of two registered quarter horses and the registry could not do anything to register the filly). Posted via Mobile Device