Popping in again because why not, again not reading anything, but it basically comes down to: Do you want him to be unique as the only Living God there is, period, ever, anywhere, in any Plane... or do you want him to be one of many? Because if it's the former, a Plane would theoretically work, though we'd need to put a lot of thought into how they work in general because we're not at the stage in MR where even thinking about Planes was necessary. But if it's the latter then Planes simply won't work because they're not infinite or close enough to be filled with countless Living Gods.