Connecting Multipart Polygons from Merge

[leahmaps]

I am trying to find a tool/process/script that will allow me to connect the outermost vertices of polygons after a merge, essentially deleting any interior vertices. 

We currently have a manual workflow for creating project areas around parcels that I hope to put into a task to standardize it and make it faster. The current workflow is as follows:

1. Select parcel polygons
2. Trace around project area parcels or export them to a new feature (dependent on who is doing it)

I want to create a task where someone can select the parcels surrounding a project (this will be on two sides of a roadway so they are often disconnected) and when prompted to go to the next step, will automatically run a process that creates a project boundary.

It is working well to use merge to create a single polygon that can be appended into a feature class with set attributes but does not join all polygons together. 

After a merge, my polygons look like this (made up of merged parcels)

I am hoping to find a tool that will then update the same (feature class) polygon and its attributes to look like this:

I am hoping to remove the manual step of having to delete the interior vertices or have an intermediate feature class just used to trace the boundary. 

Has anyone ever tried to do this before or know of a workflow that can complete this in the same feature class? I am happy to elaborate more if needed.

Thanks for any input!

[Homer]

Try the Minimum Bounding Geometry tool, using the Convex Hull Geometry Type.

[DanPatterson]

A convex hull won't work, 

A concave hull would, but there is no out of the box solution in Pro