First off, massive respect for helping your wife with such a sensitive issue. 👍🏻
Now, if she actually wants to shave with a DE or SE razor, it's generally recommended to start with a less sensitive area than the groin for body shaving. The legs are a really good starting point, alternatively the armpits are also rather tough.
However, in your/her case, if it's just to get a close shave before a laser hair removal... I seriously wouldn't bother with a DE. A basic electric body shaver should be mild enough to get rid of the hair but don't hurt the follicles. Alternatively, there are disposable razors by Wilkinson Sword (Schick in the USA) with a flexible head - means it doesn't only pivot, but actually adapts to the contours of your body. These here are what I mean. Don't let her pay the "lady razor tax" though.
As for lather, I'd recommend a brushless cream, shaving oil or a transparent gel to see better. It might also come in handy to use (shower) mirrors. Best of luck!
Thanks for suggesting it! Such a unique take on the barbershop genre and a very good base on top 👍🏻