A few points:
1.) Put a voltage meter on your vehicle somewhere. A cheap $4 Harbor Freight DMM will be good enough for this. Start your vehicle, monitor voltage. Normal engine running/alternator working voltage should be 13.8 at the very lowest to 14.7 at the highest. Turn on your lights. Does voltage sag? Rev the motor a bit, does it go back up? This will tell you if your alternator will handle the load.
2.) Standard light duty vehicle alternators are rated in PEAK amps. They are meant to put out their full rated capacity for a few minutes to recharge a partially depleted starting battery, and then drop to a much lower charging level. Your 110 amp alternator is meant to produce 110 amps for probably no more than 10 minutes; the CONTINUOUS rating will be much lower, as little as half the peak rating. Keep this in mind if you do the voltage test I list above. Just because your alternator will handle the load does not mean it will last under that load.
3.) You have an Excursion, which is pretty much a Superduty truck w/ a permanently attached camper. Same drivetrain, same engine, etc. Superduty trucks get used for ambulances and that kind of thing. There is absolutely an off-the-shelf high continuous amperage alternator available for your application that will probably bolt right in, especially if you have a diesel.
4.) A voicemail from Joe the counter guy will not hold up as proof of approval for a warranty claim on a failed alternator caused by aftermarket additions. Get a written statement from someone with the authority to make a financial decision on that level that should you add X amount of lights of X model number to vehicle X(vin would be nice) and the alternator fails, you will be covered. Failing this, prepare to pay for a new alternator ahead of time. Better to prevent a problem than "go ape$hit" on someone over a problem you could have avoided.
