I'd try to figure out what will need to be done for the future, and actually put pencil to paper to figure out what it will take to make up the cost. Unless you really want to make it a profit center - and it sounds like you do not - you'd probably be better off funding it in other ways.
Here is my thinking:
- $2,000 a year for taxes
- Assumed $3,050 average a year for maintenance. This could be 10 years that it is less than $500 annually, then all at once you have to do the roof, septic, water heater, etc.
- Landscaping $1,500 a year
- Home maintenance $1,000 a year
- Pond maintenance $500 a year
- $50 annual banjo cost - strings and setup and new head whenever necessary
- $500 in hidden costs that I'm not considering
- Assume it all increases with inflation, calling that 3% annually
- This becomes Curtis's financial responsibility in 10 years (could be less, could be more)
- Forecast it out until Curtis is 100
So, with our assumed $5,550 annual cost, when it becomes Curtis's responsibility in 2031, it will be approximately $7,500 a year in upkeep, and he needs to keep up with it until 2073. Assuming that he puts it in a trust, and the trust invests the money in the stock market at 7%, he'll need $153k in 2031 to keep it in perpetuity.
So... Can you come up with $153k in 10 years, including any potential inheritance? But wait! Your sister is included in this. So your personal contribution is only half that. And that is it for the rest of your life. $76k to $77k total, in 2031, if you invest it in the market.
Figure out what your parents estate is. I know they were teachers, so much of their worth may be in their pension which won't be passed on, but I'm guessing based on some other stuff you've posted that the estate will be sufficient to cover this expense and still have a lot left over. And if it isn't, or if you want to use that for other things, then start saving now for this. $5k a year gets you basically all the way there in 10 years, for your half. And your nephews will be working age, ask them to pitch in if necessary - charge anyone who stays there, $25 per night. Put it in the trust. Once the trust hits a certain value, the charge goes away. If it falls below a certain value (different than the stop contributing level, lower), then reinstate it.
Or, just pay whatever you need every year. You're a resourceful guy, you can probably come up with $5k every year by flipping cars or reverse stripping or whatever it is you want to do, and it will probably be easier than turning your retreat into a business.
EDIT: Certainly explore the hunting lease and other near-0 effort ideas. But really figure out if all of this is necessary. For a paid off property, I bet you it is not. Especially if your parents estate will be around 7 figures, which sounds like a lot, but isn't and is probably pretty close to what it is.