I have a 220 and 4 DC30's and have tried several different setups to try and get more range and without a doubt the best setup is adding the tuff skins to the collars and the 14'' flexible antenna to the handheld. I more than doubled my range that I was getting from the factory setup. This combo also gets me more range than I ever got from the handheld long range or the magnetic truck mount. Believe it or not, I have picked my dogs up at over 2.0mi. I normally have a constant signal up to about 1.5mi and then it will start going in and out. It also helps doing periodic maintenance. I try to update my handheld as well as the collars at least about every 4-6 months. It also helps out if after every couple hunts (especially if your hunting in really muddy conditions) you take the collars apart, undo the wire connections, wirebrush the antenna connection, and just give everything a good cleaning with some warm soapy water. At this time I usually delete all my collars from the handheld and re-add them. Also at the beginning of every hunt (if i remember), I clear all previous hunts, calibrate the compass, and go through each dog's info to make sure the collars got a full charge. It's definately a little work keeping these things in tip-top shape, but being able to pick my dogs up 2.0mi out makes it worth while!
2 miles is awesome...but I wouldn't do all this work...my mn-10 would go for years without any maintenance or battery changes unless the collor broke and got wet in the internals.
Most every thing you are saying Garmin could make a fix so as not to do all the work you do prior to a hunt...
