Food Allergies Stink - Missing My Tomato!!! Any Substitutes?

I live with someone who is allergic to things in the nightshade family. These include:

Tomatoes
Tomatillos
Eggplant
Potatoes

She also cannot have peppers - any pepper, including bell peppers.

I am a chef that specializes in Italian cooking and I have been wracking my brain trying to come up with a decent substitute. Sadly, I can't think of anything that would provide a similar flavor or texture, and before anyone suggests, I am not going to just make a white sauce instead. Alfredos have their place, but not in marinara, nor in ANY southwestern dish that I am aware of (I don't cook JUST Italian food).

So, there's my problem.

No pureed bell peppers with a dash of lemon juice, no eggplant, no tomatillos (they're directly related to the tomato, despite some claims to the contrary)...

...so what to do?

There is a company in Lancaster, PA that makes something called "Nomato", but they're loaded with sugar and corn syrup. If it was just sugar, I wouldn't mind, but I don't do corn syrup. At all.

Picky? Yes - I'm a chef!

Apricots? No. Mangos? Too sweet, won't work for things like boulognese But I'm simply out of ideas, and any help would be greatly appreciated.

Thanks!