You can do all you mentioned above but you cant eliminate some of the luck factor involved.   

I was considering paying the ACH fee, which is only $1/transaction. 

They changed how agent recruitment works, eliminating the brokerage recruiter and that salary, but not just eliminating but transferring who get's it.

It's a strict 2-year requirement.As for strategies to avoid capital gains on the sale, if your client doesn't meet the ownership and use requirements for the Section 121 exclusion, they might explore other options such as:1031 Exchange: If the property is an investment property rather than a primary residence, your client could consider a 1031 exchange to defer capital gains tax by reinvesting the proceeds into another investment property.Installment Sale: If your client is willing to accept payments over time, they could consider structuring the sale as an installment sale, spreading the recognition of the gain over multiple tax years.Charitable Remainder Trust: If your client is charitably inclined, they could contribute the property to a charitable remainder trust, receive income from the trust for a certain period, and then have the remaining trust assets pass to charity upon their death, potentially reducing or eliminating capital gains tax.These are just a few options, and your client's specific financial situation and goals would need to be considered in determining the best approach.

Using that same money instead and investing in oil exploration gets you 85% to 100% tax deduction the first year that eliminates or closely eliminates the any tax due on the Roth conversion.  

That should keep both of you happy and eliminate the feel of competition between you both.

Even if you're still paying for some of the expenses out of pocket, you've most likely drastically reduced your cost of living by eliminating most of if not all of your mortgage, property taxes, and/or insurance.

The answer to this will eliminate plumbing issues like leaking water mains or sprinkler lines.  

Recommend ACH payments for a very small-time landlord?  

Although this is probably less likely than the water leaking in through the window wells, it is possible, and you'll want to eliminate it as a cause of the flooding before deciding on how to fix the issue, because if it's groundwater, then the solution to the problem may be completely different than if it's water coming from other sources.As you consider these questions, keep in mind that water follows the path of least resistance--for example, water will flow through a gravel-filled trench much quicker than through solid earth/clay.