Congrats!!!
I had 5 horses at home when my son was born. He is two now. My setup and routines sounds similar to yours.
I was lucky in the sense that my husband got very overprotective of me and fed the horses for the first few weeks after birth. This was partly because I got really sick a week postpartum and had to be hospitalized. (Funny story- of all things I had an infection from the same bacteria that causes strangles)
It’s been tough. Two years later, it’s still tough at times. But I don’t think boarding would have made me feel better. Once I was feeling ready to get back in the swing of things, horse chores were a like a mini-vacation and critical for my sanity.
The hard thing about December is that it’s cold and you may not feel good about having a newborn in the winter weather for 30-45 min. But I don’t know how far your barn is from your house— for the first few months, babies nap a lot. Once I got over my paranoia, I was able to dart outside with the baby monitor and feed while he slept inside.
For the summer, I bought a fully enclosed playpen that kept the flies out and a clip on battery powered fan.
A lot of people have success baby wearing for horse chores, but my son was never into that. Plus I found it just made everything 10x harder.
Every baby is different. What worked for me may not work for you, but I promise you will find a way to make it work. You just do what you have to do.