Like almost everything in life Trevor there are shades of grey, even with Brexit. Member of the EEA but not EU? Customs Union? Trade deal? - the difficulty is none of this was asked in the referendum, nor properly discussed afterwards, nor planned for.
FWIW even though I favour remaining in the EU - at least for now; Cameron’s opt-out of “ever closer union” feels right at the present time but might have thrown up problems of its own down the line - I often feel that if we have to be out we should be properly out because otherwise we will be obliged to follow the rules set up by an organisation that we have no say in.
Leaving is only worth it if the gains from doing so are tangible - and (IMO, of course) they are not; mostly they are not even gains but significant losses.