I love the idea of a clear enclosure but my buddy's SSRs melted his plastic storage bin. You might consider cutting a metal piece to mount the SSRs and heat sinks and then mount that to the rest of the plexiglass box.
As for keeping the wiring neat, I used a ton of the peel and stick ziptie thingies. Also, I recommend
1 make the wires a few inches longer than you think you need... The wires should be long enough to make smooth curves or 90 degrees turns.
2 run wires through loose ziptie ties on the peel and stick mounts. Then, just keep cutting/replacing the zip ties as you add more wires to a given mount.
If this doesn't make sense, PM me and I will upload pictures of what I mean.
And now you see that Evil will always triumph, because Good is dumb!