Can I buy an extra seat to insure an open middle?
 

Mrs. SFO and I are looking at a quick Cabo weekend. F9 has a convenient DEN-SJD nonstop at only $69 OW but I'd rather not sharing a row with a 3rd person.
Can I buy an extra seat ($69 plus $45 for stretch seating) and therefore insure an open middle for the two of us??

Yes, but to guarantee it you will need to pay the seat selection fee for both you and your extra seat. I've done this before and haven't had any issues.

F9 is a far cry from a Challenger, but even with the new slimline's it isn't terrible. Maybe you'll get lucky and get a empty leg on the way back ;)

The only issue I can think of that would derail your plan is if there were standbys and if your second seat was not scanned at the gate it might be declared a no show.

I can confirm they do check. On a recent flight my wife cleared security with my BP and even boarded with it. After we settled into our seats an FA came to check if she had actually boarded.

Thanks Big4Flyer and rsteinmetz70112.

So make sure the GA scans all three BPs when boarding and explain that the third BP is the empty middle seat.
Will flyfrontier.com let me buy two tickets in the same name? Or do I need to buy the third (middle seat) ticket using my middle name as first name to trick the system?

My guess is that the third seat needs to be booked with a name something like XTRASEAT. That's the procedure with other airlines and often you must call to do this.

Absolutely. Call F9. Don't try to do this online and run the risk of one or both tickets being cancelled as duplicate bookings.

You will also receive specific instructions as to how the situation is handled. It is much more complex than simply having the GA scan the extra BP as that throws the pax count off and the aircraft can't push until the count is reconciled.

Good advice. Thanks MSPeconomist and Often1.