Hi eclipsetalk,
When you say toggle, do you mean that you want to have a link or button that triggers showing/hiding the full text on the same page?
If so, I’m not sure of an easy way to do that. The only way I can think of would be to add javascript to the template, and that would be somewhat advanced. A detailed discussion is beyond the scope of what I can go into on this forum, but I’ll try to give you some ideas.
Once approach would be to include both the excerpt and content versions of the text, but use css to make the content version initially invisible. The exceprt and content would each need their own container with a unique id (especially if you’re going to have more than one post on the same page).
Then you would add a link to trigger the jQuery toggle function, and adding code so that when the link is clicked, the css on the hidden content is set to visible, and the css on the visible excerpt is set to hidden. When the link is clicked again, you reverse that.
Here’s a link on the topic. If you google the topic of showing and hiding text, there are many tutorials that can help.
jQuery Effects Hide and Show
I hope some of that helps!