Install and Update Sandbox Solutions with CSOM

So recently, I was working on a SharePoint Online project and was looking for a way to automate the installation and update of a No Code Sandbox Solution (NCSS).

I was aware that you can install and activate Sandbox solutions in SPO with the following CSOM method:
Microsoft.SharePoint.Client.Publishing.DesignPackage.Install

There are a number of articles already covering this:

http://blog.symprogress.com/2013/07/apply-designpackage-using-client-object-model/

http://blogs.msdn.com/b/frank_marasco/archive/2014/08/10/upload-and-activate-sandbox-solutions-using-csom.aspx

The Office Dev Patterns and Practices project also uses this method to install a solution:
https://github.com/OfficeDev/PnP-Sites-Core/blob/master/Core/OfficeDevPnP.Core/AppModelExtensions/WebExtensions.cs

Just so you know, there are a couple of caveats to this approach as mentioned in the PnP documentation:
// NOTE: The lines below (in OfficeDev PnP) wipe/clear all items in the composed looks aka design catalog (_catalogs/design, list template 124).
Also, installing and activating the solution with this method will also automatically activate all Site-Collection level features, even if they have been set to AutoActivate = False

What I have found is, by changing the Major and Minor version numbers (which renames the WSP), you can also use the same method to update an existing solution

Here is my PowerShell script which Installs a solution (if it does not already exist) or updates it if the solution already exists, and the Major or Minor version number is different.

The PowerShell script:

The script is straightforward and similar to the other posts. The main difference from the PnP version being I do not run the DesignPackage.Uninstall method before Installing the solution and I also run the DesignPackage.Applymethod after Installing the solution

1) Install a Solution:

2) Update a Solution: