Upgrading the window time isn't a good idea. Because even if the window get larger, people will still farm them.

One solution would be to limit the amount of time people are willing to invest in hunting. How? Two different ideas.
- Weekly limitation on allied seal. For example you can only get 1500 allied seals by weeks
- Disminishing returns. One you get a specified amount of seals, the next hunts will reward you with less seals. For a rank A, for example, you strat getting 40 (max). After 1000 seals obtaines, you start getting 24 (max). After another 1000, you only get 10 (max). This way, hardcore player can keep hunting for as long as they please, and more casual will only get what seems the most efficitent to them.

Both of these solutions also have an added benefit: you will also need more time to get your carbon, and ilvl130 item. This way, these reward you also get from FCob doesn't seem blatantly useless anymore, and give significance to static or PU group for these raids.