I would be happy to help you make a wiring adapter to allow you to connect your 2013 Freightliner 122SD with a 7 pin round connector to your 2020 EZ4 triple axle trailer.
First you will need a female 7-pin round # PK11720 and female 7-way blade # PK12-707E. Since the 7-pin round has separate brake and turn signals but a 7-way blade has combined you will need the the 3-wire to 2-wire converter # HM48847 like you mentioned.
This will get connected to 7-way connector as follows:
Red wire... view full answer...
I took a look at the installation instructions for the Roadmaster Reflex Steering Stabilizer for Class A Motor Homes # RM-RSSA that you mention, and it yes you will need to make sure the front wheels are facing forward prior to attaching # RM-RSSA.
Adjustments to the u-bolt and the tie rod will be made after test driving your vehicle.
I did also check, and it doesn't appear that # RM-RSSA is a fit for your 2016 Fleetwood Storm, instead, take a look at the:
-Roadmaster Exact Center Steering... view full answer...
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