By "holidays", do you mean Thanksgiving and Christmas? How old exactly is your 2 year old?
Around 28 months is the "average" or "optimal" potty-training age. By 30 months you should know exactly what your child's fears are (falling off, falling in, etc., which you should not reinforce by acting scared too!). Our youngest, a 31-month-old, has already fallen in, and is therefore no longer afraid of that! In stores, at airports, at others' houses, etc., I just put down a toilet seat cover or toilet paper and bend over and hold him (just in case) for #2, which is rare, or he stands on my feet to be taller to go #1. We have the folding seat for the "diaper" bag but he has never used it. Also, if you are flying or driving for several hours, I recommend Pullups and frequently asking him/her if he/she needs to "go". We just went on vacation to California and did not have a single accident because we made sure his bladder stayed empty. So don't worry, it can be done. Just have extra clothes and wipes on hand in case of accidents! Good luck!