3/4 of an inch is pretty close. Don't know if you can get the trailer front and back much closer.
At this point, I'd take the rig on the road and run a few miles up, on back roads, highways, and interstates. Start with slower speeds and make sure it feels 100% comfortable before jumping to the next upward speed (and traffic conditions).
If you have no sway, and the steering in the truck feels strong (not like you are turning on ice), then you are probably good to go.
If you are set up properly, the steering should feel almost the same with trailer or without. The only real noticeable difference you should feel is in the gas peddle and the revving of the engine when you start pulling the trailer forward.
There again, take it on a test drive and see how it feels with your current setting.
Springs? (Personally, I would not).