Can I send an SMS message via one click or touch?
Can I have an icon or shortcut that would let me send an SMS message to a certain phone number with predefined text?
The Tasker app will let you do this (and much much more)
Once installed, add a "Task" widget to your homescreen, and have it run a "Send SMS" action. This lets you specify the target of the SMS, as well as the full body of the message.