At this point it really feels to me like some wires are getting crossed. ZING!Neither the dealer nor the local guys will install a wiring harness that is not 'approved' for the for the Limited/Platinum because of fear it might 'fry' the vehicle's electrical system.
Seriously, the wiring harness and converter for towing can be installed totally independently of the whole kick sensor debacle. The installation sheet for the tow wiring does not say it can't be installed on the Limited/Platinum and there would be no reason for it to, since the wiring is independent from the kick sensor. I don't know what makes the wiring harness 'approved' if not the install sheet itself indicating no restrictions based on trim level.
I think the people you're talking to are confusing/conflating the issue of Toyota having no official solution for installing the factory hitch on the Limited/Premium (which would remove the kick sensor) with whether they can install the tow wiring or not. (They can, whether you have a factory hitch, an aftermarket hitch, or no hitch at all.)
I am not aware of any reason not to install the tow wiring (you will need the factory converter PT725-48200 but there is an aftermarket for the 4-way harness if you don't want to buy the factory one) AND install an OEM hitch that sits below the bumper and leaves the kick sensor in place where it may/may not work reliably. Nothing would get fried.
All that said, if you don't want to or aren't able to install the hitch and wiring yourself, I sympathize with being stuck relying on the willingness of others to do it. All this uncertainty was caused by Toyota deciding they could get away with taking the vehicle to market with no factory solution for hitch+kick sensor. Madness.