Just as an update - substituting a unit facing offset into this data-based method works, but only for forward movement. Using other directions makes the unit spin continually until the order ends, at which point the unit will move in a random direction. Some other adjustments might fix this. Lucky for me I only needed the unit to move forward.
Thanks for the quick reply. I spent a half hour or so trying to do just that and for some reason just couldn't figure it out. If the persistent effect could refer to points relative to unit facing, everything else would just fall into place. Doesn't seem possible, though. Either that or I'm blind.
Has anyone been able to recreate this in an angular fashion, based on unit facing? I'm a novice, but I can't seem to create a permanent to target based on casting unit's facing or deviations of that. If anyone could help me do that - or help me with a surrogate - I would appreciate it. I'm looking to stick with data-driven so that I can easily use different movement schemes for different units.