Taxability on past invoices

[Luke <..hidden..>]

I suppose that this is an old problem, but...

In 1.2, if an invoice is posted for a non-taxable customer, and that 
customer later becomes taxable, the invoice in reports will show up with 
the original amount and no tax, but upon editing or trying to print the 
invoice, taxes will suddenly appear.

I suppose the proper action is to end the customer which was non-taxable, 
and replace it with an identical customer which is taxable, but that isn't 
always going to be the way it's done.

My questions:

1.  Is there any intent to fix this bug?
LSMB would really benefit from some snapshotting in 2.X.

2.  Are there effects beyond the edit invoice screen, to making a 
non-taxable customer taxable?  Such as amounts being altered in any 
accounts?

3.  Is it in any way possible to solve this situation retroactively?

I am thinking of creating a new customer with start and end dates around 
the non-taxable period.  Alter the database to make that the customer on 
the non-taxable invoices.  Push the startdate on the taxable customer to 
after the non-taxable period.
Then presumably printed invoices will be identical to the system's 
viewable/printable invoices.

If that will work, what will I have to alter to make it effective?

Or is there an easier way?

Regards,

Luke