My previous barn charged $5 per blanket change for pasture boarded horses.
My barn doesn’t charge extra, and blankets can be changed AM and PM. The setup is fairly convenient - the blanket box is right outside of the gate and the horses eat next to the gate. No trekking through a blizzard necessary. Another place I boarded at would only do one change per day. There’s a barn in my area that charges $50/month which seems reasonable to me. You should probably purchase a box that can be kept outside to make it a little easier.
BUT I do think you will have to come up with a number you can afford that is both worth manager’s time for the actual work AND worth risking that every other pasture boarder demands the same service. That may be a bit higher than market rate.
