My brother & I once converted a plastic ornamental (full-sized) duck
into a radio-controlled one. Installed electric motor, rudder & micro
switches for forwards-stop-reverse.
Had a lot of fun with this when we went on holiday to the Norfolk Broads
(thats a river/lake area in East Anglia, UK).
In the evening put duck into water near the staithe (local word
for quay) and wait for victims to walk past. Worth every effort