I experimented with the RAMI-75. I mounted it externally under the nose where the skid/wheel is mounted on my Arcus. I saw no improvement in forward range and it was at risk of being broken at the front of the trailer so I removed it and sold it. I was disappointed that it didn't work better.
I bought something that is similar to the long dipole in your second link and I mounted on the rear seat glare shield as high as I could get it. That didn't increase forward range either but since there was much less risk of damage I left that installed and haven't tried anything else since.