Backend user with front end access?

I've built a specific program with PHP that uses my own cms which I wrote 6 years ago. I stopped using my own cms because typolight was extremely similar in setup but more advanced and better maintained. But I never had the time to rewrite my progran for it to be a TL extension.

I am very sure I can work out how to build an extension for tl the way isotpe is set up or something like that. But pointers on how to start are welcome.

The big question before I can, or even will, start is if a backend user can also be logged in and use admin features in the frontend. I already know that the frontend is aware of any logged in backend users viewing a page, but I thought there was also a problem. I really rely on frontend administration because the people using the program mostly aren't comfortable with computers and I let them drag objects to the correct location and process the changes using some ajax techniques. All the administration for my program is done when logging in on the pages normal users can see as well (and a few extra admin only)

If it is not possible without modifying TL, then I won't even attempt the extension and save me the time.

ps, I'm looking for people to test my program if there are any bugs to be found (I'm sure there are). So whoever is interested or bored pm me...