Hi super cds.
before you do anything you had better enquire if the models you are intrested in have a receiver in them, as although they have the transmitter and rudder servo the chinese RTR models are usually controlled from a bespoke circuit board. You may though be able to scrap the electrics and replace them with standard gear ie fitt a receiver but then will the size of the hull allow you do this as everything will have to run off the one battery.
Frank