Programmatically changing layers in QGIS Print Composer?

Question

I'm trying to programmatically generate new layers from a database, and then print them using a template. Using the QGIS 2.14.10x64 Python Console in Windows 7x64. I've been following on to code from this answer and this one. Set up code:

from qgis.PyQt.QtXml import QDomDocument
from qgis.utils import iface

def load_print_composer(template):
    '''Load a print composer template from provided filename argument

    Args:
        template: readable .qpt template filename
        console: boolean if method is used in QGIS console

    Returns:
        myComposition: a QgsComposerView loaded from the provided template
        --mapSettings: a QgsMapSettings object associated with myComposition'''
    # Load template from filename
    myDocument = QDomDocument()
    with open(template, 'r') as templateFile:
        myTemplateContent = templateFile.read()
        myDocument.setContent(myTemplateContent)
    composerView = None

    composerView = iface.createNewComposer()
    composerView.composition().loadFromTemplate(myDocument)
    myComposition = composerView.composition()
    mapSettings = myComposition.mapSettings()
    return {'QgsComposition': myComposition,
            'QgsMapSettings': mapSettings,
            'QgsComposerView': composerView}

template = 'somefilename'
printcomposer = load_print_composer(template)

Things that don't work

#1 changing QgsMapSettings:

layerlist = printcomposer['QgsMapSettings'].layers()
layer0 = layerlist.pop(0)
printcomposer['QgsMapSettings'].setLayers(layerlist)

#2 Making sure mapCanvases are linked

From this answer

map0 = printcomposer['QgsComposition'].getComposerMapById(0)
map0.renderModeUpdateCachedImage()
map0.setMapCanvas(iface.mapCanvas())
map0.layerSet()
map0.setLayerSet(layerlist)

Answer 1

Confusing but functional, after muddling through Setting layer visibility in QGIS Python API?:

from qgis.gui import QgsMapCanvasLayer
map_registry = QgsMapLayerRegistry.instance()
names = [layer.name() for layer in map_registry.mapLayers().values()]
layerslist = [map_registry.mapLayersByName(names[0])[0],map_registry.mapLayersByName(names[1])[0]]
#what 
layerslist = [ QgsMapCanvasLayer(layer) for layer in layerslist]
iface.mapCanvas().setLayerSet(layerslist)
printcomposer['QgsComposition'].refreshItems()