I've worked on and off for a number of years as a freelance JPN-ENG translator, and I'm well-read in both Japanese and English. I also have plenty of friends who have been through the service economy in the US ;)
On that basis, I'm compelled to say that English absolutely has the degree of politeness required to match Japanese pragmatics in its corpus. James Clavell in the novel Shogun highlights this with different forms, most notably "thou" and "you"--dubious Orientalism in the storyline aside, the grammar he chooses to make this clear bears out in academic examinations of early modern English.
You don't even need to dig that deep, even. Compare:
A: Yeah? You need something? うん？なんか用？
A: May I help you? はい、ご用は?／どうぞ。
A: How may I assist you today? なにかお力になれることがございますでしょうか?
(Apologies for the clumsiness of the above examples; I'm a little tired at the moment.)
When my Japanese friends ask me about keigo in English, my stock answer is that English doesn't have systematized grammatical forms that constitute an equivalent, but we most definitely have pragmatics that match up.
In other words, the short answer is to look for the language that matches the usage and the situation when translating. It may be instructive to note that "pragmatics" as a linguistic term, is 語用 (the use of words) in Japanese.