White Vinegar is the go-to. 

You could justify it for the tax savings and principal pay down.Subject To with negative cash flow, is like filling a soda can with vinegar.

Example alcohol from France: make that 40%, make vinegar 10%. 

And as far as the DIY non-chemical treatments go, the most popular vinegar/salt mixtures can damage the soil over time, to the point of potentially requiring topsoil replacement.Has anyone faced a similar situation and found a solution that respects tenants’ concerns while maintaining the property?

The roach residue comes right off with vinegar so it wouldn’t be too bad to scrub them down, but the question is what is behind all the hard to reach places. 

I don’t  know you but in my experience those people have a fear or doubt in their own abilities and want to know if this will get them over that hump to reap benefits they’re looking for. example: I know plenty of people who swear by drinking apple cider vinegar every morning and the benefits - but that isn’t for me and that’s fine.

Lastly would be finding an agent who is newer, green, but full of pizz and vinegar, who is ready to overcome lack of experience with super-human level effort.

Sugar wins a lot more deals than vinegar.  

A mixture of baking soda and vinegar can help lift tough stains, too.

For walls I spray with one of the various neutralizers for pet urine on the walls. after dry,  follow up with a vinegar solution.