Personally I have had a lot of fun with a Vindicator (Yes, I know it's a loot pinata, and no, I don't fly it with this character):

8x 425mm Railgun II (Void for extra oomph. Javelin for extra tracking. Fed Navy AM for everything else.)

100MN experimental AB
3x Cap Recharger II
Sensor Booster II w/ scripts

Damage Control II
1600 rolled tungsten
Fed. Navy Large armor rep
2x Corelum C-type EANM (or similar)
3x Fed. Navy Magnetic Field Stabilizer

4 Sentries
5 light drones

2x Large Cap. Control Ciruit
1x Large Anti-Explosive Pump

Dps is about 1100 w/ drones, 850 without

Cap lasts 5 minutes with everything running, almost stable w/out (by the time you run out everything should be dead, or you're doing something wrong).

Need to be a bit careful with aggro management in some missions, and it's useless in any missions with sensor damps (Rattlesnake or Navy Domi for those).

You should still probably link your fit, since it sounds bad and you would benefit from having some more experienced players help you fix it.

From what I've heard you can PVE with a Rokh, but i wouldn't recommend it. The Raven is apparently a solid mission ship.

People constantly underestimate the rokh. it's range bonus gives it unparralelled projection (read: REAL DPS).

Take it out of EFT and into a mission.

The problem with the rokh in pve is the philosophy of hybrids and how well they don't mesh:
The base range on blasters is just too small to really benefit from the 50% bonus(and too much of blaster range comes from falloff) and rails have so much range to begin with you'll rarely ever NEED that range bonus to hit things in missions. To put it clearly:
A blaster rokh will not outdamage a blaster / sentry domi, at any range, and one with rails will only do extra damage past ~90km because the domi can't lock that far. The navy domi is pretty much the king of pve for hybrid users (as well as the vindi, though I would argue the domi's higher versatility makes it more useful)

It's also worth noting that pve ships are all about damage projection. You can survive in a l4 mission with a laughably small tank, and the only real way to measure the effectiveness of a pve ship is how much isk it brings in, which is determined mostly by how well it applies damage at the ranges required of it. Basically any kind of mission ship that relies on range to stay alive is going to do poorly, because you trade range for damage, and the conversion rate tends to be much worse than dropping a bit of damage for a little more tank.

I would say that hands down the most common mistake people make in pve is assuming they need more tank than they do. Once you learn how to fly and get the SP/ fits to back it up most lvl 4s can be done with almost no tank at all.

agreed. especially with the part where blasters have too little range and railguns have 'too much' (as in: it would be better if they had less range but better dps and tracking instead).