I would like the extension of IPv4 to be that you have the option to specify the internal IP you are trying to reach too... so x.x.x.x:192.169.0.100 for example

I would like the extension of IPv4 to be that you have the option to specify the internal IP you are trying to reach too... so x.x.x.x:192.169.0.100 for example? That would be backwards compatible and give 8 bytes which is more than enough for all futures.