Norway have been allowing 200 fans into their top league matches. I'm guessing season ticket holders names are picked at random. I don't see why the same can't happen here with crowds in relation to stadium size. For example, one thousand in each tier at Celtic and Rangers, at Hibs you could have a thousand in each big stand and 500 in both tiers behind the goals and so on. For us, maybe 500 spread out across the main stand and similar for visitors. If this happened we'd definitely have the highest percentage of regulars able to attend.
Lower down the league, in the smaller grounds like Stair Park, maybe they could copy Norway.