The latest version of PowerCLI has vCloud 5.1 API support, and allows you to add the vdcStorageProfiles section easily to the object:
$vdc = New-Object VMware.VimAutomation.Cloud.Views.AdminVdc $vdc.VdcStorageProfiles = New-Object VMware.VimAutomation.Cloud.Views.VdcStorageProfiles # $myVdcStorageProfile = search-cloud -querytype AdminOrgVdcStorageProfile -name "myProfile" | Get-CIView $vdc.VdcStorageProfiles.VdcStorageProfile = $myVdcStorageProfile.href
Complete guess on line 3, but hopefully you get the picture. 