Let's cut to the chase with your 3 bullets, all answered by the same sentence :)
Your best option by a mile is to stay with your current MBB firm and work your way towards an office transfer If your timeline is "a few years down the line" you can absolutely make this happen.
I've transfered a few times within companies and have the following advice:
How do you snag an internal transfer?
1) Build a stellar reputation - do good work, work hard, and be known as "the guy/gal" for xx
2) Build your network - network agressively (yes, networking doesn't end once you've gotten the job offer). Make sure you're known by and have allies in people who make decisions such as staffing managers, Partners (specifically those responsible for recruiting/resources and who are heads of industry/function verticals), etc.
2) b). When I say network "aggressively" please don't be needy/annoying :) There's nothing worse than someone who is obviously working the room or trying to please!
3) Look out for opportunities - look for office transfers, short-term projects, ambassadorships, etc.). Transfers can have a range of "labels" :)
4) Practice patience and be flexible - This will take time. Once you "execute", you'll also need to be ready to go at the flip of a coin. But, of course, once you've made this decision I'm sure you will be!
Bide your time, keep pushing, be smart, and you'll get there!