Erika, I have not heard of a wat that does temporary ordinations in the US, but I could ask around if you or anyone is interested.
I went to a wat in Chiang Mai with the intention to spend part of the rains there, and to do a temporary samanera ordination, if allowed. After a lengthy period of practice in eight precepts, one day after teaching English to a class of Thai and refugee workers the abbot at the wat stopped the truck we were in in the wat, and told me to get out and “go and shave head.” Waiting for me were some monks and people from the wat’s neighborhood that set up chairs for shaving heads for the future novices. I was allowed to then start to prepare for the samanera ordination.
In short, it was one of the best and most important experiences of my life to live as a monastic for a short time in a wat. To practice as a novice, to go on almsrounds, and to really go deeper in terms of practice. With the right intention, and with the right (strict) abbot and atmosphere at the wat, I feel it is a very valuable experience.
You may know this already but in Thailand, many men ordain temporarily in order to show respect and gratitude to their parents, and to also develop merit so that they might be seen by a prospective partner as a good person. I dedicated my training at this time to my parents; my sister told me my mother nearly passed out when she saw my photo in robes on Facebook…