This is freeware and has a feature to automount the last mounted .iso when Windows starts.
Install it and click the resulting desktop shortcut to set up the options.
See screenshot below.
set # drives to 1 and check both "virtual sheep" and "Autmount last image".
This will create a virtual drive in explorer and assign a drive letter.
It will appear in my computer as another drive letter everytime you boot Windows.
Then right click your iso and choose "mount (virtual clone drive).
Your .iso will be mounted and the files can be accessed by clicking the virtual clone drive drive in explorer or my computer.
Create a desktop shortcut by right clicking the drive in My computer and selecting "create shortcut".
Clicking the shortcut will allow access to the files just like any other drive.
The .iso will be automatically mounted everytime Windows starts.