I get the impression that you do not understand the principle of the Krauss-Helmholz truck. It is not a plain version pony truck just pivoting on the leading coupled axle. With the K-H arrangement it acts as a bogie with the leading wheels joined to the leading coupled axle and wheel set, which has provision for sideways movement. The larger Continental load gauge profile (up to 10' - 4-1/2"/ 3150 mm in Germany) permits the spreading out of cylinders more than sufficiently to cater for this sideways movement. Thus with a K-H truck as applied to a 2-8-2 it turns the pony truck effectively into a bogie and as far as wheelbase flexibility is concerned the chassis acts like a 4-6-2. Please have a close look at the photos on post no. 83 to see this. According to original Doncaster drawings in my possession a P2 with 21" dia cylinders is only 8' - 11-1/4" over cylinders - that is more than 17" less than permitted in Germany. For comparison an A3 with 19" bore cylinders is 8' - 9-7/8" wide. If you are going to spread the piston rod centres out by a given amount then you will have to reduce the cylinder bore size by twice that amount to keep within the same width. This brings in other problems like if you want the same power from smaller cylinders then jack up the boiler pressure, this will require thicker plates thus increasing the weight. It is all a compromise and UK locos got as big as they could go within the limits of the UK load gauge. If you can't get any useful side play on a leading coupled axle then there is no point in a K-H truck.