Well, you could start intentionally altering your set up at home, in order to get used to the set ups you'll encounter on gigs. Play a four piece for a month or two, then a five. Set up your kit so that it looks normal, rather than setting it up so that you can reach everything with ease. Make your body conform to the kit a little, and tweak your technique to make it happen. The conventional wisdom is that a drummer should angle and shift until a kit feels good, but your experience is the downside to this sort of thinking.Well if I think about it, one major roadblock is if I don't have the ideal live setup, it's always different from my home setup in that I can't have my rack toms in the same spot because I am not using a rack and I don't have a tom mount fitted to any bass drums (I still need screws to fit my tama tom mount onto the kick). I have been mounting 2 rack toms from a stand but I can never seem to get them in a good spot.
And I guess to a degree my mind goes blank on stage when it comes to anything like a big fill. Creativity is definitely stifled. I think someone said I should keep an idea of something I intend to do in my mind and use it when the time is right. I agree with that. Thanks to those who answered the question I asked.
If your mind is "going blank" when it comes to big fills, then you need to change how you're practicing when it comes to moving patterns around the kit, and improvising. But now we're getting into private lesson territory. Get with a (good) teacher, and show him or her concrete examples of the types of fills you'd like to learn. Tear them apart, and learn what sort of practice will enable you to not only play those particular fills, but also to create your own, similar fills. Don't sign up for lessons with a locally renown jazz guy if what you want is Virgil Donati fills. Having specific goals like this is good; it tells the teacher exactly what your expectations are. If a teacher can't or won't figure out these monster fills for you, move on to someone who will.
If a discussion is ever about improvement, then it always ends with "take lessons". A forum is only going to get you so far.