You either have really big square bales there or really small round bales.
One round bale here = approx 1000lbs or around 21 forty-five or fifty lb sq bales.
You can get big rounds and big squares here as well but for a lot of people a 1,000 pound round bale is beyond unusable because they can't move it. Not everyone has big tractors and a hundred head of cattle or horses or whatever or the ability to take 1,000 pound rounds off a delivery trailer. Al makes ~40 pound small squares and ~400 pound round bales and delivers (2 rounds at a time, front and rear of the tractor) but ONLY to people on the road. I've not seen anyone else delivering hay other than people carting a pickup truck load of small squares.
What is the towing capacity of the prius?
It doesn't have one. The owners manual only says "towing not recommended". That doesn't mean it COULDN'T pull something. The car weighs just under 3,000 pounds so you wouldn't want to haul anything really heavy. And of course the brakes aren't designed to stop a big load trying to push you down a hill. But I'm sure one could tow a relatively small trailer relatively short distances.
Is there a reason why you don't want a truck?
Yeah, I would hardly use it and it would cost many MANY thousands of dollars used.
We have a 1999 Ford 350 diesel dually crew cab with an 8 foot bed.
You don't have salted roads, no rusting out. Anything "cheap" or that old here would be pretty rusty.
It gets good gas mileage even when hauling fully loaded with our 5th wheel long range driving, especially if we keep it to 55 mph when towing.
Define "good" gas mileage in a diesel truck, infinity miles on zero gallons of gas?

My sister had a Suburban that got maybe 14 MPG on the highway whether it was hauling just the driver or 4 people and the 30' travel trailer. Too much engine for "commuting". Funny since the vehicle was originally built to haul dead bodies, sure didn't need a big engine or towing capacity for that, just an enclosed back at least 7' long. It's kinda like the ER, costs minimally $350 on our insurance for a hang nail because they have the
ability to deal with massive auto accident trauma. But the cost is spread over every patient, no consideration of the effort to deal with their immediate problem.