The warnings against accepting payments from third parties generally have to do with the classic scam in which the payment is for more than the amount of the rental and the traveller says the excess is for his other travel expenses, and you should refund the excess amount to him. If there is any hint of such a situation, one should run away and not look back.
But to accept payment from a third party for the actual amount of the rental should be no problem so long as you follow the same criteria for payment that you would when it comes to accepting payment from the traveler. I would not accept payment by check or money order drawn on a foreign bank from anyone within 8 weeks of the arrival of the traveller. But if these are U.S. companies, and you can confirm their credit and that they actually are paying for the travel, and it is not a case of someone claiming to be travelling on their ticket, you might treat the request for lodging as would any other of their vendors. This might even mean billing after the fact with payment due in 30 days (although I would not recommend that).
The contact could be between you and either the traveller or company making the payment. It would depend on whom you wanted to hold responsible in the event of a problem.
I am not familiar with the "travelling professional" companies that you reference. Do they actually book the rental and sign the contract, or do they just act as a "finding" service for their customers? (I am assuming that they act as a "finder.") My rental property is my second home. Before I agree to rent the property to anyone, I talk with the potential renter on the telephone. I want to establish a rapport with the renter and gain some insight as to whether or not he/she is a responsible person. Everyone's situation is different, but if it were me, I would not use a "finder" business unless I could talk directly to the potential renter before I agree to the rental.
I do not accept any payments from third parties. I have two children in their late teens. I have found that they take much better care of something (such as their laptop) if they have some of their own money invested in the purchase rather than if my husband and I pay for all of it. I apply this same philosophy to the rental payments for my cottage. For example, I did not accept a rental from a young family this summer because the payment was being made entirely by the wife's parents. I don't know the relationship that this woman has with her parents and whether or not she would care if Mom and Dad didn't have the damage deposit returned to them. My goal is to not have any damage to my property in the first place, rather than how I will be compensated for damage that does occur.
This is also the reason that I do not use the property damage insurance for renters that HA/VRBO offers. I collect a $300 security deposit from the renter. I feel that having the renter's own money at risk (rather than an insurance policy) provides a greater incentive for them to take good care of the property.
I assume from your post that there is an industry or business in your area that frequently brings employees for temporary assignments and is looking for housing for them. If that is the case, you might want to contact the company directly and market your property to them. In this situation, I would have the rental agreement with "XYZ Company" and accept payments from them, not the individual employee who is staying at your property. To me, this seems less problematic than using a "finder" company. I am assuming that an employee will take better care of the property if he knows that his employer will be on the hook for any damage that he causes. (I wouldn't want to have to explain to my boss why I "trashed" the property that I was staying in!)
These are lots of things for you to consider. Good luck and here's to your first rental!
Thank you for your replies and suggestions. Yes I live in an area where companies bring employees for temporary assignments, mainly medical locums. I guess dealing with the company would be the way to go since they would be paying for it. I've already posted on corporatehousingbyowner.com, but I wonder if there are other sites better suited for this. How long did it take to get your first inquiry/booking after posting your listing?
To be honest, I don't remember the time lapse between when I first posted my listing and when I received my first inquiry. I believe that it was a week or two. It sounds as though my situation and targeted market is very different from yours, however. (My property is a rural summer vacation rental in Maine.)
I am not at all familiar with the corporate rental market. I am assuming that someone from the corporation's HR department would be coordinating the housing arrangements, rather than the individual employee, but this is total conjecture on my part. I looked at the Corporate Housing by Owner website and it looks good. If you know of local hospitals/clinics that need temporary housing for staff, it seems worthwhile to try to connect directly with them in addition to using CHBO.