rlcowder, remember you have a 20amp alternator on that tractor. 4 lights at 55watts each will drain your battery even while your tractor is running. This may or may not be a problem, it really depends on how you use the lights and for what durations you use them. If you only occasionally run them, and then run them for fairly short time spans, you should not have any real problem because the alternator will recharge the battery when you run it without the lights. However, if you draw the battery down too low too often, then you'll end up replacing the battery prematurely.
If I recall correctly, WATTS divided by VOLTS = AMPS. So each 55 watt light will draw about 4.6 amps. If you mount 4 lights and 2 are front facing and 2 are rear facing, then logically you'd probably only power 2 at a time. So you'd be drawing about 9amps for 2 lights. Assuming you have 2 headlamps, and those are 55 watts also, then those are drawing 9amps and your current draw will be just a shade over 18amps. Assuming you also have some tail lamps/running lamps then you will have to add those to the current draw figures. But assume they use another 5 to 7 total amps? At that point you are drawing about 25amps but only recharging at a rate of 20amps.
If you are mowing the lawn for hours on end, then you are going to pull down the battery and cause yourself some grief. If you are mowing for an hour after sunset every once in a while, or if you are pushing some snow after sunset every once in a while, then I would not really be worried about assuming you also run the tractor during the day to charge up the battery. Just keep it in mind. You will shorten the lifespan of the battery, but if a battery is good for a few years and you shave a few months off its lifespan that is not a bad trade off for increasing the usefulness of your tractor.
I would also strongly suggest you spend a few dollars and get WATERPROOF switches. They only cost a few dollars more than regular switches but they don't short out or rust out.
Waterproof marine switches mounted on my tractor.