You will not hurt anything by loading the stator down with more than it can power. Stators are inherently current limiting by nature. If you put too big a load on the voltage drops to 12.6 volts where the battery then takes up the slack and provides the rest of the required current. But that also means your battery is getting discharged instead of being charged up.
This is situation normal for most quads at idle with headlights on. The max output of the stator in watts is proportional to engine speed. At idle the output is pretty meager and can't keep up with the headlights, so the battery is draining even though the engine is running. But when you run up the engine speed the output increases. The stator (through the voltage regulator) is able to provide enough power to drive the headlights, and more. The regulator then pushes the voltage up to 14 volts (+/- 0.5 volts) which is *above* the battery voltage of 12.6 volts. This causes current to flow backwards through the battery charging it back up.
You need to see if you have enough stator capacity to drive all the loads and raise the battery voltage to 14.0 volts at a medium fast engine speed (say 3000 RPM). That way, on average over normal engine speed ranges, the battery on average keeps charged. At idle it won't, but on average (which includes higher output at higher engine speeds) it will keep up.
Here's how to tell: Take you meter and set it to measure "Current" on the 10 amp scale. Uusally this involves moving the red meter probe over to a special "10 amp" input jack as well as setting the scale properly. Remove the main fuse coming off the battery, and insert the meter across the two fuse clips in the harness. Now all current (other than the starter motor current which goes though it own heavy gauge wires) will pass through the meter and be measured directly. Leave the meter in position for the rest of the tests. Turn on the headlights and set to high beam. You should see the current being drawn by the headlights. Note the polarity.
Now start up the quad. The current being drawn out of the battery will be diminished since some of the load current is being provided by the stator through the regulator - the rest is coming from the battery. Rev up the engine. Look at the current values and the polarity. If your stator can keep up with the load you will see the current go to zero with increasing speeds, reverse polarity and climb back up. The reversing of current polarity (current direction) is where you've reached the break even point where the stator is powering (barely) all the electrical loads. At higher engine speeds then the break even point you are measuring the battery "charging" current.
HID lights and LED lights are much, much more efficient than stock incandescant lights in terms of watts consumed versus lumens out. If your stator can't keep up with the new lights then keep the new lights and scrap the stock lights. There are some really impressive you tube videos of HID and LED lighting systems for quads. The only down side to them is the initial cost ($$$).