Trailer for hay storage

I am considering buying a trailer of some kind to store my hay. I board, but am self-care, so I tend to keep 30-50 bales at a time. I currently have all my hay delivered and stored in a corner of the hay loft, but climbing the ladder is difficult for me due to an injury (which will not be completely healed anytime soon). I want something mobile so I can save a little bit of money by picking up the hay myself - right now, the hay loft requires a hay elevator which the hay farm is happy to bring and stack the hay for me for an extra fee.

The two obvious choices are an enclosed cargo trailer or an open landscape trailer.

My concern with a cargo trailer would be air circulation - though it would be opened 1-2x/day so that I can feed my horse.

My concern with a landscape trailer would be that it’s open, and I wouldn’t want any of my hay damaged from the weather.

Does anyone here use either method for storing hay? Any tips or suggestions?

A vented cargo trailer ?

An old stock trailer plus a tarp?

I have used a cargo trailer to store around 50 small bales. Trailer is not well vented, hay was very dry when loaded, worked fine for me. FWIW, I live in a very dry climate.

Would an open trailer with a tarp to cover the hay be alright? I don’t want any of it to end up unfredable either.

I’m in Alabama for reference. All of your options would result in molded hay, at any time of the year. It’s just too humid around here.

Cargo trailer would need to be vented at least. I tried this in the summer and almost lost an entire load of alfalfa. Not good.

Utility trailer and tarp- well the neighbors store hay like this and just lost all of the 50 bales on the trailer due to rain. It’s got a wood floor… wood holds moisture.

My hay storage is an old general store/house on a cinder block foundation, not ideal and hay will go bad somewhat quickly but it’s all we have. It does not breathe enough and I’m too paranoid about the wiring to run a dehumidifier or fan all the time.

I store hay on an open trailer … BUT it’s under a shed. With three sides open. I grow hay… I do not recommend tarps or an enclosed trailer for long term storage at all in my location. Hay “breathes” it absorbs moisture readily and slowly gives it up as the air dries. Right after baling is the most critical as it goes through a “sweat”. Good Air circulation is an absolute requirement for me.

If you’re in an arid area, the tarp or trailer may work for you.

I sometimes put hay in a modified stock trailer*, which works fine for me in our climate–on the dry side, except lately.

*My ventilation openings are high on the side walls.

In the winter we store bales of hay in our 2-horse straight load.

You could not fit 30-50 bales in there, but you could probably get 15-20. Not ideal in an emergency.

No problem with mold/damp - we are in Massachusetts.

I’m in Maryland if that helps sort things out.