I'd say it can be a serious challenge, but is possible. One time before I tried this at a "well-watered" vacation spot and relapsed. Most recently I was working the steps and committed to AA and had no problems at all.
Does he have phone contacts for some people in his meetings? Encourage him to pick up the phone before picking up the drink. I know that is real easy to suggest and harder to do in the moment, but someone very early in sobriety in my group who was on vacation recently and on the verge of drinking used the phone and it helped him stay sober.
Best wishes!