What if Dragon swapped locations every time it was killed?
Part of the problem of top lane isolation is that early map objectives are far away from top lane. Taking dragon's spot and moving it permanently to top lane would just cause the duo and solo side lanes to switch places, but what if Dragon spawned randomly at either top or bot river arena and then switched locations each time it was killed until Baron spawned? You'd have to get rid of or figure out something to do with Rift Herald (or just have it swap too?) but it would draw some kill and assist gold away from the duo lane through contesting that objective, and it would give mid/jg/top a reason to group and do stuff.