Could you run this on network block storage like EBS? I assume those have pretty high latency as well, even with high IOPS volumes?
If you care about WAL write/commit latency, you could provision a small-ish EBS io2 Block Express device (with provisioned IOPS) just for your WAL files and the rest of your data can still reside on cheaper EBS storage. And you might not even need to hugely overprovision your WAL device IOPS (as databases can batch commit writes for multiple transactions).
But the main point is that once your WAL files are on a completely separate blockdevice from all the other datafile I/O, they won't suffer from various read & write IO bursts that can happen during regular database activity. On Oracle databases, I put controlfiles to these separate devices too, as they are on the critical path during redo log switches...
One thing that I try to achieve anyway, is to spread & "smoothen" the database checkpoint & fsync activity over time via database checkpointing parameters, so you won't have huge "IO storms" every 15 minutes, but just steady writing of dirty buffers going on all the time. So, even if all your files are stored on the same blockdevice, you'll less likely see a case where your WAL writes wait behind 50000 checkpoint write requests issued just before.