Back when we played around in the Lost City, the Quick March spell was considered to speed up travel through the jungles. It was eventually rejected.
It seems like a nice spell, but no one uses it, because "double daily movement rate" combined with "must sleep 8 hours" is a real drag. To be effective you need at least 1 ally who has twice the movement rate of the slowest PC and who can skip out on 8 hours of sleep. Not only that, it lacks built-in effects for a lot of traits that should affect this - Very Fit, Less Sleep, etc.
Another big problem is Haste. A wizard with Haste-15 can reliably boost an entire small party's Move up +1 and maintain it forever. No additional FP loss, either. So you end up with people calculating the estimated overall travel time and then trying to split off time with Haste instead of Quick March. In DF level terms, that's a better choice and less costly in lost time.
Here is a rough draft pass at how to revise it.
Doubles a subject's long-distance travel speed. At the end of the day's march, the subject loses 8 FP in addition to the normal FP loss for encumbered travel. This additional FP loss can only be recovered by sleeping, at a rate of 1 FP per hour. Subjects with Doesn't Sleep are awake, but must rest quietly to recover. Subjects that neither have nor expend FP don't lose any FP, not do they need to sleep, but cost to cast is doubled.
Duration: 1 day's march (maximum of 12 hours marching, or 24 hours from casting time, whichever comes first.)
Cost: 4. Double cost on subjects that neither have nor expend FP.
It's possible to consider this FP loss as a physical effect, in which case Very Fit should halve the cost. I'd phrase that as "This is physical effort; Very Fit halves this normally. FP can only be recovered by sleep, at a rate of 1 per hour."
At least at first glance, this seems about right - costs you +8 FP, need 8 hours sleep to recover it all, even if you normally don't need 8 hours of sleep. You can stay away with Doesn't Sleep but you can't ignore the effects of the spell. You can push on with sufficient FP (like our Druid who was like 18) but eventually it'll catch up to you.
A caveat restricting this from being used on vehicles, etc. - maybe it only works on willing, sapient subjects - would prevent the "Quick March Zombie army" or "Speed Your Wagon" effect without the need for doubling costs for those subjects.