I didn't have any problems communicating with or booking any providers using my US number. However, I also wasn't too concerned about hiding anything, so if extreme discretion is a concern then an Irish SIM would definitely be the way to go.
I'd also recommend reaching out to more established providers. Same rules for me in Ireland as in the States (or anywhere really); no reviews allowed = pass, deposit = pass, general uneasy feeling talking, texting/Whatsapp = pass. Overall the established providers on this site are far less a risk than anything state side (and a far more reasonable with their rates).
Be safe and have fun.