Hmmmm, I will not question your reasoning for wanting to do this. I am sure others will. But, I think GM designed it to work that way for a reason and as far as I know, there is no way to adjust those limits. I suppose a dealer might be able to do something like that with their Tech2 devices, but I don't think it is a commonly done modification and it might not be possible at all.
I will be monitoring this thread however, just to see if someone else has a more definitive answer for you.
Good luck.