I have used my (group owned) a/c for a business trip and the company refunded the cost. I flew it solo and I did have the choice of taking a scheduled flight, driving or taking the train. It was significantly quicker than the car or the train and was only about 20 mins slower than the scheduled flight and about £30 cheaper. I submitted the claim as normal with a comparison to the airline ticket and it was paid.
I even got told off for taking a colleague up for a bimble as, if we had been killed it would have been a major setback for the business.
Pulse 1, I think your company's response is a little over the top. What you and your friends choose to do on your own time is none of the company's business (unless perhaps it is illegal). The fact that the company has no critical cover is an issue for them, not you. I hope you are extracting maximum value
