PGPool for Postgres load balancing, where to sit it
Direction:
I would definitly recommand this step by step tutorial that may point you to the right direction. This is the one I used when setting up similar config. You can adapt it to your needs eyes wide open.

Multiple PgPool:
The tutorial seems long (and it is: 6 parts!) but the part related to setting up multiple Pgpool is less than half one of 6 parts (see part 5 and 6). Even if I could consider setting up pgpool as a pain, objectively, this part is not the worth (consisting in setting up ip arping and watchdog). If you have already been through the rest for configuring one pgpool and stream or wal replication that will not be a problem.

Decentralized or not:
This may be only based opinion, but if I had to setup pgpool redondancy (I did not), I would prefer placing pgpools along postgresql servers in order to simplify my setup and make the whole thing accessible from outside "as if" it was a simple pgsql server. App and database layers stay good at what they are supposed to do and could stay technically "agnostic" to ascendant/descendant layer.