One could remove the fridge from its place and sprinkle a layer of "Boric Acid" under the "fridge area".

Sprinkle it over all the carpet and one inch over the edges.

I also think the people who prey on people looking to make money in RE with little work and $ are immoral as they're making money selling a system that they know won't work (it's like selling shovels to gold prospectors and pointing them to a spot where you know there's no gold) Perhaps I could have been more specific but a sprinkle of hyperbole makes life interesting. 

I applaud you for your forward thinking, but you may want to sprinkle some of these properties in with more conventional construction until you are certain the investment will work for you long term.

If it is in the walls and we know what it may be (tobacco, pet, etc), we have a recipe (tsp, rinse, seal, paint)... or if it is from the floors, we clean or even pull the flooring (seal underneath refloor, etc)...One simple carpet one I use is sprinkling the large (13.5 lb)  bags of baking soda into the carpet (if carpeted)... work it into the floor with stiff broom, so it gets into carpet to pad.

It may sound hard to believe, but you will forget spit details and writing them down keeps everyone honest.I also try to take a long term view and sprinkle in some extra for the other side at the end of the deal. 

I always feel these questions are rarely on the up and up, but here goes.Attorney response: it depends.Depends on desired target return, risk tolerance, active participation willing to make, etc. etc. etc.Fire and forget (forward all mail to Tahiti): Drop all $10M with 3-5 HML funds sprinkled around the USA at a solid 8.00% ROI.Work now/Play later #1: 2-3 ground-up multi-use facilities in central Texas (my back yard) paid for with mostly cash.

Sprinkling old buildings and providing for two separate drainage systems in a building build with one is also a costly challenge as is storm water control.

Your time here will be well spent.Thanks for sharing your info which is sprinkled with challenges, but, not insurmountable.My suggestion would be for you to start with bird dogging  and/or wholesaling.

I am a former USAF guy (with some amrny national guard sprinkled in as well) and we do buy and hold up in South bend but have also bought houses an hour south and have looked as far south as Peru so have a small bit of experience close to your duplex.