I don't think it will be possible to do the bit stuffing properly using 11.0592MHz as 12MHz is the magic number when it comes to USB but don't let me stop you from trying.
Using 12Mhz, there are lots of spare cpu cycles to do other tasks so if you did get 11.0592MHz working then you should still have some spare cycles to do other tasks.
It would probably be a lot easier and greater chance of success if you tried double the frequency at 22.1184Mhz even though the fastest AVR's are specified for only 20MHz, I've used them reliably at 24MHz as long as Vcc is 5 Volts.
Using this method You could use a different divider for your baud rate generator (just divide by 2) and have many more CPU cycles to do other tasks.
Using 12Mhz, there are lots of spare cpu cycles to do other tasks so if you did get 11.0592MHz working then you should still have some spare cycles to do other tasks.
It would probably be a lot easier and greater chance of success if you tried double the frequency at 22.1184Mhz even though the fastest AVR's are specified for only 20MHz, I've used them reliably at 24MHz as long as Vcc is 5 Volts.
Using this method You could use a different divider for your baud rate generator (just divide by 2) and have many more CPU cycles to do other tasks.