I'd contact Linear/Mr Bicycleman to see if he has any of the add on deraileur mounts left so you can mount a front derailluer to stop the chain derailment. He doesn't have many left. Hopefully I didn't buy the last one...
Another option is to purchase the return idler so that it takes some of the slack out of the chain. The chain tube addition would also be a good idea.
I'll take a picture of my Linear 2.0 with derailleur post when I get home.
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