I may be wrong but the rules as far as I know are the same as for drones; not above 400ft agl.
If you do a PFL 'not closer than 500ft from any vessel vehicle or structure' then you're in the clear.
RC Modellers mostly go by SMAE codes of practice but there are a few who seem to think the rules don't apply to them and they have sole rights to fly over 'their' flying site.