If I might make a suggestion for the bookkeeping? Create a sheet that has four bands on it: near, close, far, and very far. The PCs begin the encounter in the near band, at the bottom of the sheet. The opposition begins in the center of the far band.

Since most of the squishy types like Controllers and ranged Strikers will want to stay more or less where they started, they provide something of an anchor for everything else, but you can also treat it like Tetris: when the lowest range band empties, everything slides down until it has something in it.

For keeping track of adjacency inside a band, use horizontal position of tokens. The PCs will probably start adjacent to one another in the near band, while the opposition might be scattered in the far band. If someone's moving from one band to another, you can slide them within the band to keep track. If two individuals are flanking, you can put their tokens on opposite sides of the flanked model; if they're just both adjacent, they can be put next to each other.

So long as the tokens don't get shifted, it's a fairly quick, abacus-like system for bookkeeping. You could also use counters for things like rough terrain and so on.