I recommend you don't reinvent the wheel. There are two amateur radio bands in the US the FCC sets aside for line-of-sight remote control for planes and surface craft (boats, cars, etc). The RC community has determined standard frequencies and uses the same modulation and protocols as on other license free bands, so as long as you follow their guidelines you can get equipment off-the-shelf that allows you to use your general license to access RC frequencies that are uncluttered by other unlicensed users.
RC frequencies are located at 27MHz, 50MHz, 72MHz, and 75MHz. License free users can only use frequencies in the 27MHz and 72MHz bands. The RC community has already created a channel list for all the available frequencies:
You can find transmitters and receivers that work across that range from RC retailers, though it's unlikely that local stores will stock Amateur Radio band RC equipment. They can be special ordered, or found from online retailers.
You can often find suppliers by searching for keywords such as "RC", "50MHz", "75MHz", "transmitter", and "receiver".
Once you have a working system at your desired frequency, then you might want to improve on it. Starting with a good system makes the next step easier, rather than starting from scratch.