I have Tiagra brifters, FD, and RD and I am running 11-34T cassette in the back and a 52-42-24T on the front. It pushes the limits but it does work if you dial it up right. You just have to avoid the stupid extremes (52->34 or 24->11) and be a little gentle with the front shifting but it works wonderfully. There are tricks like putting washers in to make the FD a bit wider that you can maybe try to help eliminate a little rubbing if needed.
I think switching to a friction shifter for the FD would make this setup work in all situations and it's the route I may go eventually.