anthropic,
I have considered similar projects to just lease a pond from neighbors and do the management under some type of arrangement. (Because my pond "building" budget keeps disappearing due to family budget priorities.)
I would definitely go talk to the rancher friend first. See what she would allow or support. If everything is a firm "No.", then there is no need to pester your lovely bride.
If you do get approval from the rancher, and then your wife, there are lots of potential baby steps between initial improvements and your huge "optimal" renovation. Culling skinny bass for one or two years might make a significant improvement. If you post your fish sampling notes on Pond Boss, I predict you will get tons of advice on the proper slots for culling.
Finally, if you do make substantial investments, I don't think some typical Airbnb guests will undo all of your work if they are just out for family time. However, if the ranch was advertised as "managed pond with 12# LMB", then I think it would get heavy pressure over long periods and your big bass would either get fished out, die due to excess handling, or become extremely hook shy.
I think you have a wonderful opportunity, but you and the rancher would have to come up with a pretty comprehensive set of rules to keep all parties happy.
