The specialists you called were over thinking your question.
The easy solution is to buy a full fare flexible ticket, (direct from the airline) that allows free changes i.e. a proper Y or C ticket for a departure date 9+ weeks from now. If you book a ticket with a Lufthansa* their full fare rules allow you to keep calling up 1 day before your ticketed flight and postpone it for a few weeks/months as many times as you want up to a maximum of 12 months. If you don't use the ticket within 12 months of the original departure date you lose it though.
The full fare ticket won’t be blow your socks off cheap, but, A) it will be cheaper than a last minute full fare ticket and B) a full fare ticket is higher up the waitlist priority in case of a fully booked flight - giving you some additional security that you will be able to travel when needed. The cheapest P and Z class tickets are the first candidates for denied boarding in the event of a over-booking.
*These are Lufty, Swiss and Austrian rules, other carriers may be different.