Without one you will need to prove what you had before in case of divorce. Otherwise everything that could have been acquired during the marriage would have to be split half half.
Idk about US rules but it sure helps a lot if you marry in Thailand. Bang rak (Amphoe in Bangkok) is famous for that.
After that the marriage just needs to be registered at you embassy. And later an entry into your home country is thousand times simpler (at least for all European counties) !
Edit: Switzerland is sure one of the best countries when it comes to simple government paths
It took me 2 weeks to get all papers and my wife needed a little longer. Then we went to bang rak at 07:00 ( they accept only a few couples per day!).
Add on: make a prenup!!!
I prepared it via email with Siam-legal and we went to the office in Bangkok the day before marring (prenup must be there or it’s not accepted by Thai law!)