It could be done with the addition of a weighted keel and being clever with the servos etc but you will need to sort the sail rig out as its all wrong at the moment.
it only cost a tenner.. and the running gear came from a toy boat out of a skip,
as flat sheet lead keel and the pocks out of is bum , that will make your eyes water …
rudder on a stanard servo motor 350 out of toy home made shaft and coupling buggy power pack though 10amp esc…………also built a plank on frame sea queen for the same bash complete with hre majersty….Larry..
{looking to converting to rc , by connecting the rudder to main sail}
That kind of arrangement involved the main boom having two lines that had a cross-over on their way to the tiller quadrant (an arm each side of the tiller), and a centering spring on the tiller as a form of self steering (look up "Braine gear". It would try to keep a set heading to the wind. If the boat headed nearer the wind, sail pressure relaxed, the tiller would steer away from the wind and vice versa. An entertaing black art to set up.
This is an alernative to radio control, and they would probably work against each other.
You could always set the sail at half out, great for running across wind, passable for heading into wind and workable downwind, with the radio just working the rudder.