Is this some kind of challenge or something, seeing as you're going for charity aswell?
Not really officially although we've made it into a challenge by booking our flights already. Meaning that we have to make it to Croatia within 8 days in order to catch out flights. It's actually part of a charity called Link Community Development, who set up Hitchhiking trips every year to Morocco and another random destination (this year it's Croatia).
3 people is a bit of a crowd. You're probably less likely to get rides with that many people.
This, aside from spending too much money is probably my biggest worry. I do understand that two is a far better number to attempt this with, but since we are leaving on Monday, there isn't really much we can do short of leaving someone alone to try and rectify this. We're just going to have to do the best we can and hope for bigger vehicles to take us or like you suggest, use public transport.
Have you ever seen hostel?
I haven't actually, although it was suggested by a friend of mine the minute I mentioned my little trip. Safe to say I think I'd rather watch it once I return safely from my trip. Although I think starting this thread has worried me ever so slightly.
