When i wrote my D2 off my saving grace was all mods declared as it had a full post crash inspection, most but not all mods picked up, it cost nothing to tell the ins coy of the mods and nothing extra to pay for them, however i was assured if they had not of been told i would of been out of over 10k in total. All my vehicles get insured and anything declared the day of fitment.
It beats me why people would run the risk of themselves and their family for the sake of a few quid, yes bills can add up, but your family,kids etc are more important than money ever will be.