The correct set of SolidStep Manual Fold-Down Steps for your 2015 Dutchmen Denali Lite 246RK is part # LC678041. I know you said you had a 27-1/4" doorway but the above will work just fine for this as the bracket it mounts is not 28" wide. view full answer...
At one point the Flexco Steps part # SMFP-2100 that you referenced were listed as having the same width you need of 26-1/8 inches between the mounting brackets. We now know that the dimension is really 27-5/8 inches. Since we don't have a step that matches directly you'll either need to move your current brackets or have new ones installed with the Outriggers part # LC301704. The steps of this kit have an 8 inch rise whitch is pretty standard and would be a great option. view full answer...
Since your RV doorway measures 27 inches in width the correct SolidStep kit to get is the part # LC791574 as it fits a doorway width of 26 to 29-7/8 inches.
This kit also is designed for doorway threshold heights of 35 to 44 inches from the ground. view full answer...