The way I've seen it done. They get two rooms. One for working the other for staying in. In case they both get booked there set. On cost I'm not sure but would imagine it would only be fare to split cost.
imo, it works, only if the two ladies know each other very well on a fundamental basis, and I don't necessarily mean intimately.
Again, imo, best if each is well established and can deal with potential compatibility issues.
Most of the times that it seems that the workouts fail, it's always an established provider mentoring a total or near total newbie lady.
As we all know, many newbie ladies just don't work out in the real hobby world.
Pair-wise, the one provider takes care of all the TCB and tries to educate the newb. Nothing wrong with that, imo.
Pair-wise, if one lady is making way more appointments than the other, that's where the friction might begin.
Not sure if I can offer much in the way of advice, except for the traveling pair to have a very well established foundation well before they start traveling.
Keep the finances separate during the trip.
Don't loan each other money.
Split expenses on a daily basis.
Keep some sort of diary of expenses, etc. so y'all have a record in case of disputes.
A lot of great luck to ya!
I know some cities (ask me via pm) that would welcome some travelers singly or doubly. Just ask.