Dipper, the NDK Triton is listed by NDK as a day/weekend double, and consequently is well below the norm for doubles one might select for a 10 day venture. A ten day trip out of a 30 inch wide double is tight for storage as it is, because performance doubles with the fine ends needed for speed have much less storage in bow and stern compartments. Some so-called high volume doubles achieve added storage volume by fattening the ends, which compromises their efficiency.
In short, before you eliminate all 30 inch beam doubles, you might demo a couple of them and see if one fits your needs for speed. To wit, our 22 ft long 30 inch wide 1993 vintage Current Designs Libra (not the Libra XT, which supplanted the earlier Libra) is plenty fast enough, and adequate in storage for 10 days only if we deck load lighter gear. To make a boat large enough for 14 days (market: for hire guided expeditions) CD's Libra XT has fat ends, at the cost of more form drag. We have paddled both, and the difference is remarkable ... our old boat beats the newer one to the beach every time.
I suspect some careful scrutiny of specs for Seaward's offerings may point you at a boat or two to try.
As well, reconfiguring the forward bulkhead on a stock "performance" double aftward to enlarge usable dry storage up front, and perhaps re-siting the bulkhead separating the rear compartment from the cockpit may similarly help. We did this on a Pygmy Osprey Double in the construction phase from the kit, which converted it from a nice weekender into a killer 10 day boat, with minimal deck loading.
Moving a bulkhead is actually fairly easy, with some contortions, but if an aged overweight guy like me can do it, any fit paddler should be ble to manage it.