I'm also using smaller coolers so that they are more manageable. One thing that really helps is having the proper containers to fit inside the coolers. I have built up quite a collection of the square cambro containers with the color coded lids. I've got them from 2 qt all the way up to 12qt. They stack easily, have volume markings on them for reference and are easy to handle...can't say enough good things about them.
I appreciate that link to webrestaurant. I usually look there for baking supplies for my wife. I actually thought about the insulated bags a long time ago but never got around to checking them out. Combined with a fold up cart/wagon I think that’s my best bet.