I think there is a lot of money and resources involved.
In addition to hiring this vet, you'd have to hire a nutritionist or keep one on file, or make sure your vet has experience and knowledge in equine nutrition. You'd also have to hire a trainer, or two, to work with these horses and assess their riding skill level, if any, and also re-acclimate them to normal horse life. You'd have to find other barn helpers with rescue horse experience, because a lot of them would get aggressive with their food and possibly with people as well. You'd have to have enough space for nice big turnouts, preferably with grass, which grass land can be expensive in places where there are droughts or water shortages. You'd also have to study up on the intricacies of contract writing and local equine law.
In addition to all of that, you'd also have to have LOTS of money to pay for the things that you might not think of besides the hay, feed, and shavings for stalls: wormer, brushes for each horse, halters and leads, etc.
And that's of course on top of the power bills, farrier bills, water bills, mortgage.....