Schengen air travel confirmation and private aircraft

One of the requirements for the Schengen visa is for the applicant to present confirmed travel arrangements, most commonly air travel. This is usually done by booking a ticket and printing out the confirmation.

On this occasion however, the 'host' owns a Gulfstream G650 and wants to pick up his guest in Perm and return with her to Rome. After a proper visit in Rome, he intends to return to Perm where she will alight. What should he provide the applicant with in order to meet the Schengen requirement? Neither host nor guest has done this before so there's no experience to rely upon.

Yes, it's possible to purchase tickets from a commercial airline and then to abandon them once the visa has been issued, and this option has been discussed and summarily discarded as a 'waste of money'.

It's also possible to use Acrobat or Photoshop to mock up a confirmation, but this idea has also been discarded as 'tawdry'.

The host could also send his flight plan that he will file, but this will be in the future and it's indefinite (especially the return trip). Also, he could send a copy of the registration papers, but this would not indicate anything other than ownership.

She cannot simply write "arrangements have been made" because they would need to see something. The form says "State who and how and present corresponding documentation", but nothing more informative is given about the documentation. What should the applicant enclose with her Schengen application that will demonstrate her capacity to travel when a conventional air confirmation is not appropriate?

The first option is being held in reserve as a last resort.