As far as I know, there is NO frequency that allows a no-license 2-watt transmitter other than 27 MHz CB. IIRC, the 72 & 75 MHz bands are limited to 1 watt, although it depends on how it's measured - 1 watt RF output corresponds fairly closely to 2-watt DC input (P=EI) at the transmitter final stage. I don't know which way the FCC specs for RC control are written.
No-license operation, at much lower power levels, is permitted on the 49 MHz and 900 MHz bands used by wireless mikes and wireless telephone handsets.
In contrast - note that pocket size cellular phones use somewhere less than 1/2 watt of RF output. They work over longer ranges because the cell sites are on towers, of course.
FWIW: Any remote-controlled system based on simple signals or even two-tone DTMF frankly scares the crap out of me. It's far too easy to falsely or maliciously trigger the thing. I'd *really* rather not have some jerk send the firing signal when I have just armed a K motor and am still only 4 feet from the pad.