What manufacturer? You can do it via USB and have a script disable mounting or mount on command if you'd like, but if you have a Pi it won't be any different if you use the same network. Still the RT68U I suggested is only $40 if you want to have a secondary network, and you probably have a router laying around that supports custom firmware.
I think if you have a Pi the best thing you can use it to prototype if you want dedicated hardware for what the pi is doing, but if you are buying it for the purpose of OP, its not a good use of resources, and anything a Pi can do an old laptop or desktop can do it better and prototype it with no cost and probably better software, but if power usage is an issue dedicated hardware should be considered.
I think if you have a Pi the best thing you can use it to prototype if you want dedicated hardware for what the pi is doing, but if you are buying it for the purpose of OP, its not a good use of resources, and anything a Pi can do an old laptop or desktop can do it better and prototype it with no cost and probably better software, but if power usage is an issue dedicated hardware should be considered.