Ok, so I'm cooking up my plan here.... If it's the air in the jar that causes the expansion issue (which makes sense since the sugar doesn't change temperature as quickly) what if I use Ziploc baggie feeders instead? I have some Imrie shims, so I could use a shim to facilitate enough space for the baggie, and then I could just remove the 2nd box entirely (or fill it with frames, whatever you guys think is better). So I'd have box, shim and baggie, inner cover, outer cover. I'd still warm up the syrup of course. What do you guys think of that?