Upgrade your OTA antenna. Doesn't sound like you need MUCH more - so forget about the bat-wing clip-on and get one a bit bigger, that can still use a piggy-back mount on the dish arm (if that's important to you).
One thing - avoid using diplexers for OTA if you can, and if you have to use an amplifier, put it as close to the antenna as possible - this can mean issues with where to put the power inserter. It gets REAL messy trying to use an inserter on a shared (diplexed) feed cable.