A size 45 is a nice large size boot. I do think that these have features of a boot manufactured after the war. I've seen Luftwaffe marked side seam boots, so side seams are not a guarantee of WWI vintage. Several things stand out. First is the sole. Normally, the sole of a WWI boot will have a double layer of leather starting from about the ball of the foot extending to the toe. Yours appear to have one piece going from the heel to the toe. Secondly, the heel plate is narrower on the bottom on an imperial boot and the leather insert has numerous nail heads showing, whereas yours does not. Finally, as you mention the top of the shaft is cut differently. You normally would only see a sloping cut on an imperial cavalry boot, but it would be more pronounced. I think what you have is a nice postwar pair of boots.
Regards,
Chip
