In people's opinions (and I know there are lots of factors) is a fork offset of 60mm with a 72 degree head angle a bad geometry for a large front rack that will haul groceries and other medium weight loads (plus occasional large, heavy loads)?

I've tried to read up on geometry but I still find it slightly confusing.

The only way you'll know for sure if you can haul loads , and how big of a load, on the front is to buy a basket and try it out to get real raw hands on practical data.

Good wire baskets are not that expensive..........

Wald makes a lot of good wire baskets for front and rear.

I have the largest size Wald baskets front and rear. If I try to put heavy loads in front, yes, steering is affected substantially.
SO!
When I get a load of groceries, I separate the load out between heavy, dense objects and lighter, bulky things. My bottled water? I break up the case and put it in the back baskets, along with the canned goods, milk, and jars. That leaves me with a few bags of things like chips, vegetables, bread, and the like; those go up front.

if you measure the distance from where the headtube would reach the ground (if it were extended to the ground in a straight line) and the center of where the tire touches the ground you will have a trail measurement. Most bikes have about 60mm of trail. For large loads you want close to 25mm of trail. You can sometimes achieve this by having your forks bent forward so that the head tube angle is steepened and the wheel is further forward thus reducing trail.