I like option 2 better but would like most to use an approach which is compatible going forwards.
I suppose
Maintaining future compatibility can be done by continuing to manually creating inter account transfers and manually deleting the corresponding imported transactions until the built in Inter-account transfers account is available
but if option 2 will never be available, living with option 1 (a user created Inter-account transfers account and disabling the Inter-account transfers tab) is probably more efficient.