Joan,
Great question! I would strongly suggest that you seek the advice of a tax professional on this matter. There are indeed many options available for traveling therapists. However, I must caution you that you should be very wary of companies that offer huge per diems and big housing allowances. While it is very enticing and lucrative for the therapist, it exposes the traveler to potential IRS penalties.
I spoke with an IRS agent specifically about this topic. They have clearly defined guidelines regarding amounts you can receive. For instance, a company may offer you a $2,000/mo housing allowance. But, the area in which you are doing an assignment has "reasonable and customary" housing costs for much less. If you are audited, you are going to pay penalty and interest - at a minimum.
Just make sure that you get a professional's advice before accepting any pie in the sky reimbursement plan!
Bon Voyage!