That's one of those spots that simply is what it is trash wise and to hunt it is a challenge and learning process.
The better hunting area's have already been mentioned, along drive ways, etc, so I would hunt those area's with the 6" coil and do so at a snails pace just cover small area's and be somewhat selective tone and tid wise starting out. Get the easier targets first, if possible. Once one gets some good quality hunting time in with their detector, target I d's do have some meaning, bottle caps do sound a tad different, most of them, and have a bigger feel to them then do most coins. The same with big iron , cans, and so on. I don't use discrimination nor notching ever, so can't suggest anything pertaining, too.
As you describe it, there has to be a few older goodies hiding among all that trash. Keep in mind, though, farmers were a fairly poor lot back in those era's. Good luck, sounds like a fun challenge. HH jim tn