There are seventeen areas that have riding maps you buy with Allied Seals. They cost 250 each. That totals to 4250 Allied Seals for all of them (which is 250 above the cap).

Doing the weekly elite mark bills gives you 100 Allied Seals per mark slain, which comes out to 43 weeks. That's 9 weeks short of a year, which you'd then adjust for each A Rank and S Rank mark you manage to get credit for (only 40 Allied Seals each), which is difficult because of what I've already mentioned in the original post.

There are seven more riding maps to get for Heavensward areas, except those cost Centurio Seals instead. Thankfully, those are easier to get because Hunt marks in Stormblood areas give full Centurio Seal credit, while Allied Seals can only be obtained from Hunt marks in the original A Realm Reborn areas.

The biggest problem is the fact you don't get Allied Seals from Hunt marks in the expansion areas, and/or the fact that people will just solo them and not wait for others. The difficulty in soloing these fights (or lack thereof) is a contributing factor to this.