I live in central British Columbia (winter), and have no barn. My fields are a 1/2 acre each, so more than a paddock but not anything huge. Each field has a shelter in it that faces the front fenceline (so it’s a run through shelter, only 1 sided).
I have my trailer parked under a covered RV shed/Hay shed, and use that as my tack room and tack up area. It’s a pain. There’s an old shed that the previous owners used for tack/feed with a covered side for the wood shed. It’s an eyesore and not worth putting money into sprucing it up (it’s not that good structurally). We think we will tear it down and rebuild it. Small wood shed on one side, one covered groom stall with tack closet on the other.
In the meantime, I have added gates to my run-in shelters so I can close them in their shelter if needed. It’s not ideal at the moment, but they wear sheets to keep them dry, have the shelters and lots of trees for different shelter. Plus, means I don’t have to handle turn-in and turn out or daily mucking.
My other 3 small fields need to be sprayed, seeded, and then wait. They do not have a shelter so we need to build a run in that straddles the fence of the two main fields. I debated making it also come outside the fence and doing the tack shed there. It’s possible based on the location, but the current shed and planned position is also right by a well and easy to add a spigot to.
ETA: I only have 2 horse currently, about to get a third. It depends how much land you have, how many horses, and what you style of horse keeping is. I came from boarding barns where they were stalled at night and in paddock or small fields during the day. The more hands off approach is working well enough for me here, and it lets them be horses.
I should also add that just outside my two fields that have shelters, I have a small shed that has room to store up to 16 square bales, and covers a frost free hydrant and has power. I have motion lights plugged in, and my heated auto trough is wired there. I only put him 8 bales (more than a week’s worth of hay for two horses) and use the other side to store the immediate necessities – halters, fly masks, a seasonal blanket/sheet, etc. I have a separate hay shed off the side of my 25 x 50 shop and my grain is all in a freezer in my garage. When we build the new shed, we will build a small box around the freezer and add a cabinet for extra supplements, etc