The Mamotion bracket wasn't long enough to get out from under my eaves.  So I made this bracket and used PVC to connect two of these brackets together.  One bracket goes onto the RTK unit and the other to the exterior wall.  In my case I had tapered siding so I had to use a combination of the wedges to get the arm level coming out from the house.  The wedges are included in the zip file.

I printed in PETG with 4 perimeters for strength.  I wasn't sure at first if this would be strong enough to meet the needs of the RTK to be nice and steady, but I've used this for a while with no problems.