I would recomend that you contact the tunnels and find out what they each got to offer...
If you plan on dooing 5-7 houers of tunnel i would recomend that you spred it over at least a week in small session max 10 min otherwhise i would say that you are waisting a lot of monney cause i dont think you can make fyssicaly especialy if you plan on dooing lots of freefly/style
Jesper
www.tunnelcamp.dk