So the first thing you want to do is to avoid something like this:
All of the arrows are snag points. They can all be avoided by taking a little prep time and secure the wires to your vest with velcro, tape or zap straps.
Now depending on the radio you have the option for an extended antenna is possible and should look something like this:
Notice how neat the wires are. This also allows you to keep your radio up front in case you need to change frequencies.
As for the comfort level, most headsets come with different sized earpieces. You should be able to mix and match to find one that works. You can also contact a hearing aid company, they can make a mold of your ear and custom fit your ear piece. This is by far the more expensive way to go.