I too have had some sharpening challenges with the file. What has worked for me is only break out the file to reestablish a straight edge if the head has been shot into the ground or hit something that's really buggered it up.
On new, or fairly so so sharp heads I use my med, fine, and ultra fine Lansky stones. Just use them without the rod and guide, I lay the stone flat on the back edge of the Trailmaker 3 blade head and push to the front tip, turning the head on every pass, going to lighter pressure and finer stone.
Be sure and use the honing oil, with a little work a new head will shave with little to no pressure applied. I like to hold my arrow about mid way back up the shaft and be able to just lightly brush the blade down my leg to shave as a test of sharpness, if hair flies off it's ready.
If you wanted to take a couple of your Lansky stones in your pack when hunting for touch up, there very lightweight and small when carried without the box, rods and base.
The Lansky is what I aready had and has worked good for me. And when I say get them scary sharp, I mean it.