LEDE? It's a comlete system with bunch of packages. You can do what You want - it's clean Linux. If there's something missing, You could write Your own program/package/script. It's flexible and open. And that's why You need as much flash as possible to avoid extroot.
If You use minimal image even 8MB flash will be enough, but try to use more services, install packages and popular 16MB is not enough.
As routers're going more and more powerful why should we be limited to basic services? Todays routers are like servers in not-so-far past: compare R7800 to i.e. basic Sun SparcStation II