A "leap to Flowrestown" won't be manageable. Pian en Luries will have to expand northwards slowly to reduce spawns, and a prodigious sum of adventurers will be necessary around those mountains.
As tempting as Flowrestown is, I remain convinced that the most realistic "next step" towards colonizing the Divide Mountains is Sallowtown, or maybe Unterstrom. Actually a join colony in Sallowtown between the Lurian Kingdoms and the Véinsørmoot would be very interesting.