I generally don't recommend pre-souring.
A Flanders Red needs Brettanomyces yeast to get the right flavor profile. There are two basic ways to make a sour with Brett (traditional vs modern), and in either case you want the yeast to produce flavor before souring the beer.
L. plantarum is best to use with my fast & funky method, but it won't work if there are any hops present. However you can use L. brevis or Sour Weapon P, which might not be quite as fast as L. plantarum, but they would be much more suited to overcoming a low hop rate ... Otherwise you should use yeast with no hops.
Hope that makes sense.
For low hop sours, I've read up on the modern methods and they all seem fairly simple. I plan to co-sour a Gose this way with L. Plantarum next, adding a hop tea to stop souring after 1-3 days.
However, for a sour IPA, or any other high IBU beer, would pre-souring be the only option to really get any or much hop bitterness? Can a hop tea be boiled for an hour adding hops like a normal brew boil to get bitterness/flavor/aroma contributions?
I've considered a normal mash, no hop boil (short), chill like normal, transfer to a corny keg at 95F (easy to seal & CO2 purge), let sour on L. Plantarum for 1-3 days, transfer back to the kettle and boil/hop like normal before a 'normal' ale yeast fermentation. Would this be the best sour IPA approach?