I am surprised that you can only find one person offering this, because a simple search on AW turns up more than that. (They may be lying, of course.)
I have no idea as to the level of demand you will get - as ever, it will depend on your location, amongst other things. But yes, doing a separate marketing campaign for this would make sense for the reasons you give. You could advertise potential tours in various cities and see what demand there is, for example.