When you first pick up the bike spend a good 30 min riding solo.
Get use to the bikes characteristics before your wife hops on the back.
The brakes are not a strong point on a KLR, take some getting use to.
Check/adjust tire pressures for the load, manual states 21psi front and 28psi rear loaded.
Some people go higher.
Just some thoughts.
Highways will not be where this bike shines, stick to the back roads if possible.
It can do it just fine, but can numb your butt from the vibes.
Of course the 16t sprocket will be a saving grace.
Keep an eye on the oil level if traveling lots of interstate.
And Most of all: HAVE FUN!!!!!!!!!!!!!!!!