FWIW:
I carry minimum liability on my 89 300E. These older MB's have no market value whatsoever. If it gets totaled, I understand the risks. Any upgrades or additions I do, I know come out of my pocket and make no difference to anyone but me. I never expect to get my money back. I do these things to make the car more valuable to me alone.
Unfortunately, all the electronic upgrades you made to your 190E have no value to anyone, even a tuner. The performance upgrades, maybe.
If it were me, I would take all the electronics out if you have access to the car and start on another. After all, it seems as if you really enjoy all the mods you did so just think: Now you can do it again and fall in love with another car!