All it takes is the slightest suspicion, and the wife starts to dig. And do they dig !!!! Whatever they ask, it should be deny, deny, deny.
You cannot afford to become secretive, be late home from work, leave a paperwork trail, pin code on phone, password on PC, larger than normal cash withdrawals, and the like can trigger the Spanish Inquisition.
Even buying flowers unexpectedly, or buying new pants, changing deoderent and more attentive to personal care can make a women suspicious. And woe betide you if you glance at the girl with the nice arse and legs as you pass by in the car - if she's in the car with you.
Sometime 'normal' behaviour is necessary for a while. I've had too many close ecounters including some very stupid mistakes I've extracated myself from, but I wouldnt be cocky to say I've perfected it. As I tend to punt 20+ miles from home, there is the risk of a accident, breakdown, speeding ticket etc, and the why were you there question?
One of the safest ways is when you have to be in an area for business. Hard for those who are office based, but I am on the road, so there's more flexibility. I still risk being spotted by someone who knows the family who might ask why I was coming out of a block of flats etc. I do prefer punting in winter as the dark nights act as a good cover.