So you haven’t had the baBy yet right ?
Lol - you may be old hats at travel but travel with a baby is a lot different, we started with ours when they were very young - 3 months in country and 5 months out of country - however there was a steep learning curve .
Keep in mind you may or may not have a baby that cries a lot - think about people in room next to you , lol , looking for a self contained unit might be best .
Don’t take this as anti Mexico ( we’ve been to Riveria Mayan areas 6 times in last 8 years and we love it , much prefer it to west coast ourselves ) or anti travel with baby - we’ve done stuff with three kids under six , including an infant - but I’m just giving you a heads up on some issues . One of my kids was a horrible traveller , even as an infant , the crier , the sickly one , the cranky didn’t like change one , and one of my kids ( youngest ) was easy as pie - and our oldest was what I’d call “ average “ , so fingers crossed you get an easy one !
Also flight is about 5-6 hours - then drive to Tulum is about another 1.5 hours . Baby may not be too cooperative- or they may be great , problem is you won’t know till baby comes .
Personally I would not go too remote - if baby is sick ( they can get sick fast ) at that age you should be near proper medical facilities. Ones that have paediatricians , 5 months is young . .
At this point I would not assume everything will be back to normal by Xmas .