If it were me, I'd definitely get the trash piles sorted through, and cleaned up. Nails & wire have away to keep coming to the surface. Not good in a pasture where animals are grazing, let alone tractor tires. Once clean, seed with something short lived like oats or buckwheat. I'd keep everything clipped down tight to prevent weeds, and other undesireables from going to seed, and do a Fall planting of your choice with a slit seeder.
Frost seeding works well here, but don't know that your temperatures there get cold enough to do that. Here, it's normally done the last 2 weeks of Feb., to the first 2 weeks of March, when the ground honeycombs, and pulls the seed in, basically mimmicking Mother Nature. I've been using this method for 20 years, and have had good success with it, until this year. We had a mild Winter, but finally got 2 days where it was supposed to drop to 18コ, and 10% chance of snow. Here is a picture of the day I seeded. We ended up getting about 2-1/2" of snow, insulating the portion of bare dirt I'd prepped, and it did not freeze well enough to honeycomb. Growth in those 2 area's were poor enough, I disked it up, and reseeded this Spring.
However, where it was seeded in the existing stand of hay, it did very well. I'd clipped it late last Fall down tight after growth had stopped. I wanted to switch the main grass crop to an Endophyte free fescue for horse hay. I also added Blue Grass, Tuukka Timothy, a bit of Red Clover, and a white clover by the name of Renovation Clover at the rate of 1 lb. per acre to boost N producton to feed the other grasses for a few years. Too many years I've broadcast Urea before a supposedly 60%-70% chance of rain, and didn't, so basically lost 40% of it due to evaporation.
The picture of the standing grass/clover is what I got broadcasting into the existing stand, and I'm pleased with it. Fescue was sown at about 12lb. per acre to choke out the Rye Grass, and seems to have worked well. The Red Clover did very well, considering I sowed it @ 2 lbs per acre.
Reading the specs for the Renovation clover, it was recommended to be sown at 2-3 lbs. per acre. The seed dealer warned me to only do 1 lb. per acre, because it can become invasive. If it wasn't enough, I could always sow more next year, as the seed is viable for a few years. Glad I took his advise, as it is as thick as I care to have it.