I am a humble hearthling and have yet to deal with this particular issue in game, however it is something that appears in nearly every combat video of W10...
Placing a building post while in combat.
It's used by players great and small to stop somebody from continuing in the direction they were moving. Effectively you create an impassable wall out of nothing (or maybe a semi-permanent one out of a bough or stick), which allows the person who places it to more easily catch up to whomever they are chasing. I personally feel that this goes against the spirit of the game. I've also seen it used to stop animals running away, hell I've used it to stop animals from running away, or change the direction they are moving.
I offer one simple solution to this problem. You should not be able to construct anything which requires a sign post while you are in combat. This wouldn't affect crafting items while in combat, only building.
I also offer a more complicated solution which would require more work on J&L's behalf, and honestly is less preferable than my simple solution. Construction zones could be made passable until the final part is added. I fully realize that this would likely create more issues than it would solve, however it is still a possible solution to sign post cheese.