So I'm just stuck in a lane where I can't get fed (except free farm and denying them heavily) while I can't really leave my lane for plays either.
This is honestly fine as long as they can't leave lane either.
Set aside the fact that I think if you're smurfing on Renekton you should be killing your lane opponent a lot. I honestly think you're over complicating Silver by playing Renekton. You're picking a champion that is strong in the context of trading in lane via high damage, sustain and a good kit for all-ins, but requires more finesses/judgement when playing in teamfights, and even 2v2s to be honest. How does this translate to winning? It means your jungler generally has automatically strong interactions on the top side of the map if they want to interact there. The Silver jungler is not going to realize this or know how to use this advantageously. They are going to farm and only look for ganks when the enemy lane is pushed up to tower. They have no idea how to work middle-of-the-lane ganks because they haven't played with laners who know how to set up middle-of-the-lane ganks. Renekton does not translate into teamfights well (at least not nearly as strongly as a lot of other champions).
http://oce.op.gg/summoner/userName=taylorswift420
This is a smurf I've been playing at Silver for a bit. There's Heimerdinger, Singed, and AP Alistar as the most played champions. None of these champions are particularly mechanical (most of the mechanics just revolve around dodging stuff).
If you look at my Lee Sin record at Silver, it's terrible, because Lee Sin is harder to play, and in a Silver environment shit like Amumu does more by pressing R in a good spot than a full Lee Sin combo does.
On Heimerdinger, I really rarely group with the team unless we have baron and it's a game winning push. The majority of the game I'm just hard pushing lane, and getting ganked by the jungler (sometimes I die, sometimes I kill, I honestly don't know much about Heimers limits yet). But I'm tying a laner into lane, getting more tower pressure (honestly I don't even deny that much farm), and turning the rest of the game into a 4v3 for the most part if the jungler wants to stop my push. There's no special wave management, there's nothing mechanically hard about putting turrets down. It's just brute force.
Singed is actually something I've played on my main a lot, so I won't really go into that because it's on the try-hard side for me.
AP Alistar is really simple in silver. You go into lane with crystalline flask, when they're about to take their first cs, headbutt them away and take a cs. Back off until your headbutt on is on cooldown. Repeat. PEOPLE AT THIS ELO DO NOT KNOW HOW TO RESPOND TO THIS. There's no concept of "that's a 14s cd so I have free reign on this lane for the next 14s". They just take the Headbutt and stand back confused for 14s until you Headbutt them again. You will wear them down with the Headbutt damage, go back and get a dark seal when you've exhausted your mana pool. Rinse and repeat. When laning phase is over, just look for the time where both teams do the aram, the enemy team will clump up at some point and go for the Headbutt Pulv (Flash if you have to) and you will take away over 50% of everybody's health and your team can do the rest. It's honestly that simple.