You guys may have pin pointed the correct way to do it but I found an alternative and since I'm working on a prototype / proof of concept project, quick and dirty is what I'm after.
In the app's config.json file, I added the widget and placed a position node/element with it in the json. I'm guessing I may have actually stumbled onto the correct way to do this but I'm not sure. i haven't retested the widget in the header controller with this setup but I think those widgets are locked into the default panel size. Placing this widget in the "1" spot (near the home button) is sufficient for my need and actually preferable because I need to be able to move the window to interact with the map under it. Anyway, here is the code I added to config.json in the app root where the "width" and "height" control the panel the widget panel's size:
{
"position": {
"left": 55,
"top": 45,
"width": 650,
"height": 500
},
"placeholderIndex": 1,
"id": "_5",
"positionRelativeTo": "map",
"name": "SplicingSchedule",
"label": "Splicing Schedule",
"version": "1.1",
"uri": "widgets/SplicingSchedule/Widget",
"config": "widgets/SplicingSchedule/config.json"
},