Definately see if you can add a dry standing area, ideally hardcore if you're allowed which you could put a round bale feeder on (I have a regular feeder which is in two halves so I can just roll the bale and flip it in, but I put a haylage net over the bale first before it goes in so it limits wastage far better than not using one). You could get one of those bell type feeders which would be even better as they keep it dry as well (I just cant afford one). If you dont have any area of hardstanding for the horses to gather round their hay then you might well end up with a serious bog meaning probable mud fever etc.
I have a tack room and stable block but you'll definately need somewhere dry and as big a shed as you can afford. Maybe one of those solid plastic Costco type ones would work? Also lighting, along a bit of driveway where I park the trailer sometimes at night I screwed in solar powered motion sensor lights, they dont light up a huge area but would probably be handy to see round gateways etc.