I feel like that would be creating a level of complexity that would just get in your way more than help. The idea behind auto-complete in the first place was to keep things simple, not have a ton of different commands / key shortcuts to learn or remember, just a framework that offers a variety of completions and lets you take control from there.
If you look at Document > C/C++ Options... > Completion Options, you'll see some additional options you might find interesting.
1) Subword matching can be turned off situationally (auto-complete, list-symbols, manual completions, aka Ctrl+Space)
2) For manual completions (Ctrl+Space), you can configure it such that the first attempt does prefix matches only.
What does this mean? Instead of having two commands to invoke symbol completion with subword matching or without subword matching, you do not have to think about it, and you can just configure it such that it initially just does prefix matching, then if you hit Ctrl+Space to force symbol completions, then it would do subword matching. If you have auto-complete turned off, that means the command for prefix matching is Ctrl+Space, the command for subword matching is Ctrl+Space, Ctrl+Space. In fact, because subword matching is hard and can time out, you can even hit it a third time and see if you get additional results (because of caching or luck, depending on how much work it gets done before the timeout).