Sounds like you’re on the right path…You’ll definitely want to do some estimating for your upload buffer since you’ll have 2 targets on the gateway.
Check out the ‘sizing the upload buffer’ section in their docs: http://docs.aws.amazon.com/storagegateway/latest/userguide/GatewayCachedLocalStorage.html
- There is a formula they provide, w/examples that can help in sizing the upload buffer.
You can always add more upload buffer capacity as you need (up to the limit of course), so feel it out. Same goes with the local cache storage - although your intentions for the cache are pretty clear.
If there is anything else, give us a shout!
--Justin