I wouldn't worry too much with the nitro on the back - I don't think you'll get it unobtrusive without a lot of work. Got anything you can screw over the top to cover it up?! (maybe some plastics - you could route a cover cavity in and have a screw on plastic cover, pretend that it's meant to be there?)
If not a cavity cover, I'd be tempted to sand a high grit until it's at some level of finish that's acceptable and leave it.
I wouldn't worry too much with the nitro on the back - I don't think you'll get it unobtrusive without a lot of work. Got anything you can screw over the top to cover it up?! (maybe some plastics - you could route a cover cavity in and have a screw on plastic cover, pretend that it's meant to be there?)
If not a cavity cover, I'd be tempted to sand a high grit until it's at some level of finish that's acceptable and leave it.