Bath door handle - second opinion

[93Sovereign]

Hi,
I’m nearing the end of my renovation and one of the final tasks is to install a new bathroom door handle. This is one of a couple jobs I didn’t want to take on myself. I hired a local door repair shop. The tech didn’t want to do the job as he believed there was an 80% chance of ruining the door when drilling the hole for the latch assembly - ultimately he believed the latch assembly is too big for my 1 inch door. Before I move on to plan B (whatever that may be), I though to post here to see if anyone has been in a similar situation and might have some advice. I’ve attached a number of photos. I suppose at the end of the day I am curious to know if anyone has had success installing this Airstream handle in a 1 inch door and, if so, what size bit did you use to drill the assembly hole.

Thanks in advance for any insights.
Tom