Regardless of the legal and regulatory aspects of the business, given the current overly litigious state of our society, any rational space tourism entrepreneur (and even more importantly, his/her investors) will be concerned with insurance and liability issues. These are inextricably entwined with the regulatory issues because, to the degree that the government regulates a business, the business (at least in theory) gains some degree of indemnification (though this legal principle has been severely tested, if not broken, in recent rulings against the tobacco industry, which was judged to have misled its customers despite the fact that it met the government requirements of health warnings on packages).
As in the regulatory discussion, early space tourism activities will establish precedents, and should be planned in that light. For trips on government vehicles, there will probably be no issue, since the government has very deep pockets in the unlikely event of a successful lawsuit against it. However, any private entities participating in the activity would also be at risk.
For now, the best general approach to dealing with this issue is probably the one discussed above—the “Ship’s Company” approach--in which the passengers form their own corporation for the purpose of carrying out their “research.” This will not eliminate liability, but will mitigate it, depending on how cleverly the various contracts are written, and the number of intervening corporations provided as buffers against the deepest pockets.