I’ve just googled to find out more about mixed grazing. My MIL who has horses questioned putting donkeys with horses, but all I can find out is that the donkeys are prone to Bott and Lungworm if grazed with horses.
I don’t know if it’s an Old Wive’s Tale, but donkeys are supposed to be good dog and coyote killers with their hind feet. Dogs can really wreck a horse running it into a fence or attacking it.
You could hire me for a fee. Depending on where you live, etc… I don’t know the fee.
I can’t say whether a burro, goat or another horse would be best for your purposes, but my family owned a burro for a few years. They’re absolutely dead easy to care for, we didn’t even need a farrier after I read up on maintenance. Our burro was extra sweet on a neighbor that she’d do anything for and gladly carried around his grandkids when they visited. Burros aren’t quiet sometimes, our Jinny brayed like a guard dog would bark, but with a volume no dog could ever match. This may or may not be an issue to consider.
On the other hand, you could get a cashmere goat and make your own sweaters!