Some "years" ago I compiled socks from https://3proxy.ru/download/ to have a simple socks proxy running on different ports for each external IP of my router but I don't have anymore a developpement repo ready to compil it again.
I don't found any simple socks proxy with dedicated outgoing interface in LEDE sofar, is there one ?
Or does a repo with 3proxy binaries exists ?
I "installed" the SDK, and fetched https://github.com/zCookie/openwrt-3proxy as source and only modified the Makefile as :
PKG_NAME:=3proxy
PKG_VERSION:=0.8.11
PKG_RELEASE:=1
Tinyproxy has a pull request pending to add support for SOCKS (see https://github.com/tinyproxy/tinyproxy/pull/64). Maybe you can compile it yourself and replace the default Tinyproxy package from the repository.