After ramsacking Tops I find out that Benny has left. Someone meets me outside and tells me I'm to catch a boat and meet Caesar. He has Benny. I play through a bit more of the game and when I decide to go to the location to to catch the boat, everyone is hostile and I am forced to kill them. Now there is no way to get to the Fort and find Benny and the Platinum Chip. Anyone have any suggestions other than loose 15 hours of play and start over.

You can still get to the fort. You just need to get on the raft and look down. But since you decided to piss of Caesar after Caesar already gave you amnesty, it's going to be harder.

If you reload right before wiping out the Legion settlement you should be able to sneak in while wearing Legion armor as a disguise. Be careful as the Praetorian guards at the fort will see through your disguise but at least it will get you in the door.

You can get all the way to the top of the Camp with the Disguise. I used that to get the Brain for Rex.

There is a Guard and Dog both at the door to Caesar and immediately inside it. I am not sure you need to get into the tent to get Benny, I never allowed him to leave Tops Alive.

[Edit]

you only need the platinum chip if you are doing Legion, House, or Wild Card.

All of which you will get the chip back when you head to the Bunker.

You don't need it for NCR.

In you case. Wipe them out.

I didn't need the chip, as I'm going NCR, but I REALLY REALLY wanted my revenge on Benny.

I stormed the place, killed everyone (required a Stealth Boy to kill Caeser, thats a tough tent), and put a round between Benny's eyes as he was on his knees.

I felt a bit better after that.