If you have a good signal past 200 feet, you probably aren't Part 15 compliant.
For FM this is most of the time true, however if conditions are right, a Part 15 FCC certified FM transmitter can send its signal well beyond 200 feet.
For AM, well this is a hit and miss best guess because of the variables such as ground conductivity, the grounding system utilized and the coupling/tuning efficiency to the 3 meter antenna. Ive seen 70mW in a very well designed Part 15 2.19 system send a signal out to 3/4 mile no problem. Daytime of course. Night..well at that point 200 feet or so is about as much to expect for a clear signal, after that...it ends up buried in the skywave noise.
The only way to be sure is to get your hands on a field strength meter that reads that low.
According to the rules, a quasi-detector with no AGC is the industry standard for measuring AM transmission field strengths. These are easy to build and can be made just as sensitive and accurate as the infamous Potmac FS unit the FCC engineers use. I know...I built one and use it monthly to verify my CC station's emission limits. I calibrate it to a fellow engineer's Potmac FS and every time, it indicates the same readings as the expensive Potmac.
A good communications service monitor can also serve as a fairly accurate FS meter for close to nth decimal point measurements, at least within the ball park.
After playing around with the "carrot on a stick" method for a number of years and always being let down by the poor range even at 3/4 mile on a good day with moist ground, carrier current is the way to go with AM. Though many state the lower band is best for carrier current, I found it to be opposite and that the upper portion works best for my installation. My TCU-30 couples to the neutral and grid ground lead in's right off the drop. Fortunately that ground drop is isolated and with the addition of 4 ground rods at 15 foot intervals, 5 watts was all that was needed to get my signal down the line and into listener's homes and without all that nasty hum.
If your really wanting to reach more listeners and expand the range of your station LEGALLY, then carrier current is the way to go.
Although LPB is not manufacturing new CC units, Radio Systems does, however their unit is limited to 10 watts carrier power while one can find an LPB unit on ebay that can pump out 3 to 5 times that power level.
And its great to see a 1982 design work so well with a 2000 era C-QUAM exciter. Chris never expected to see one of his transmitters mounted into an LPB TX as an exciter. I bought 3 more of his units as spares plus one that was un-assembled to have individual parts on hand if needed.
And if you cannot find an LPB or cannot afford a Radio Systems unit, there are plenty of schematics and plans out here on the web for building a transmitter and coupling circuit.
2 watts coupled through a 10mH inductor and a .1mf 3kv ceramic cap onto the neutral line will work with fantastic results! However to maximize the RF induction, use an antenna tuner such as an MFJ 900 and add 6 more turns to the upper portion of the inductor coil and add two 500 pf caps across each of the variable caps and with the above 10mH inductor and .1mf cap, you got yourself a very effective coupler that works just as well as the infamous LPB TCU-30 and TC-8 couplers.
Happy building and broadcasting!