The ticks are worse in my area this year than last year.
Yes, bushhogging helps - I just bushogged -- it doesn't help that much when large acreage is involved and you have pine and cedar trees all over the place.
Don't say cut them down -- most of them aren't on our property and I don't cut trees down anyway, unless lightening hit them and they died.
Unless your horses are going to be on that 160 acres the rest of the summer, it is honestly too late to start a feed-thru like garlic, which does work to about 85% efficiency.
It can't be fed to horses with digestives issues, ulcers, or prone to colic.
Powered garlic is what needs to be fed, as it has had the allicin processed out of it. Allicin in raw garlic can possibly cause anemia.
You can't spray enough to keep the horses tick-free when you can only get to them twice a week and they're roaming that much non-maintenanced land. Spraying as often as you can is better than nothing at all. Soak their tails, below the bone, really good, spray their legs and chest areas.
If you have MTG, rub some MTG lightly on their ankles, around their knees, in their forelocks, under the jowels, ears, crest of neck, tail docks where you didn't spray with fly spray.
MTG is really oily but it is sulphur based and ticks hate that smell. If you can manage to not put it on too heavy (maybe use a paper towel), hopefully you won't find them painted in dirt when you go back out.
I might also consider buying crushed garlic at the grocery store, draining the liquid out of the jar, mixing with a bit of water and using it as a fly spray on their legs and wipe it around their forelocks and under their jowels.
Yes, some horses have absolutely horrible reactions to tick bites. If I miss a tick on my Arab, he will knot up in his tender areas to where he looks like he has a tumor
I keep hemerhoid ointment on those bites as it does a great job of reducing pain/itch/inflammation.
Given your current situation, that's the best I can come up with that won't cost a fortune and might last a few days