Route Planning with modified settings producing inaccurate results

I tried using ABRP to plan a simple trip towing a trailer. I have a configuration for my vehicle with trailer where the reference consumption is set to 1.35 mi/kWh (same as what the truck says on the trailer screen) and also “maximum speed 55 mph” - I drive conservatively with the trailer and don’t exceed 60mph and slow to 55mph on steep hills.
The route is 102 miles long with substantial elevation gain. The ABRP route plan comes out saying it will take 109 kWh and with 16% SOC on arrival. This turns out to be very inaccurate. The Rivian route planning app, also configured with the trailer but with no speed limit set, estimated we would have 33% SOC on arrival.
The ACTUAL DRIVE ended with 38% SOC.
I feel like ABRP is ignoring some settings or is miscalculating somewhere. I can’t feed in any values that lead to a result that matches the real world or the more accurate Rivian estimate.

https://abetterrouteplanner.com/?plan_uuid=cc85ac05-46cb-4cf3-9963-6ecf4f82bbad