Assign a percentage of a resource to an entity (task) for project management

First, yes, I have read all the documentation and, if it’s in there, I can’t find it. Please point me to it if it is there already. I will happily eat crow if it is.
Second, I think I can kludge this by creating some dummy resources to assign additionally to an entity/task to achieve the partial assignment, at least to an acceptable extent. I have to test this.
Here’s why I want it. While it’s true that I want resources to focus on a task, finish it, and then move on to the next instead of task-switching, there are some tasks that have wait time built in, such as a request to have a server environment configured somehow. That may take weeks, but use maybe 5% of the resource’s time. I would rather not have to break the task into multiple pieces; I don’t need or want that level of granularity or precision. In those cases, it’s OK if I see the assigned resource in the Chart view with two tasks stacked simultaneously. I have a flag (image) to indicate this type of “wait” task and, bless your heart, I can see that flag right there in the Chart view. (Phenomenal!) I figure that, if I can do partial resource assignments to a task, I can stack such tasks and have the duration calculations take the partial assignment into consideration.
If you know of another way I should be doing that, please let me know.
Thanks!