I've had three experiences of this- once myself, once with DD and the final as a host.
Instance 1 - When I was 16 we went on a trip to our twin town - in Germany. This necessitated an 18 hour coach trip, and once there we were staying with families who we only met on our arrival. And singly, not in pairs. Ok, it was the '80s so different times but I really, really loved the experience and it was a whole week, not a single night. No mobiles, no internet, managed to call home once the entire week.
Instance 2: DD, aged 13, went to spend a week with a family in a town in France. Were given name of host beforehand together with contact numbers. The children were in pairs and loved it. She only spoke to me once the entire week and that was when I rang the hosts! Again, an 18 hour coach journey either way and visits whilst they were there. The adults with them (Brownie leaders) had the numbers of all hosts and and saw the children all day, every day.
Instance 3: I hosted two girls from the above twin town when they came over last year. They spoke to their parents twice - once when I gave them the phone on their arrival and once mid week. They spent the days with the other children who had come. We weren't DBS'd before hand but hubby and I had them anyway due to work & hobbies.
IF they can provide contact details for the host families ahead of time (and I don't see why they can't do that in this day and age!) then I think he really will enjoy it. Most mobile phones will work in different countries (DD's did in France from UK) - you might just need to check with the provider ahead of time to confirm / activate though. 7 hours away doesn't seem too bad to me either.
Talk to a few of the other parents of team members; if you can all ask for the contact details ahead of time then there shouldn't be an issue.