i agree, chris, that simply changing the overlap settings will not do the trick, since MP still assumes the 4:3 orientation of the camera is with the wider dimension perpendicular to the direction the solo is flying. i have set up the MAPIR setting in MP so it's using those in its calculations. MP has a checkbox within the "survey (grid)" settings for "camera top facing forward". i assume that if this is not checked, it assumes the camera is in a 90-degree position. however, for the single MAPIR mount, it's a very simple mod to orient the camera top first, check that box and have all the settings be similar to if i was using the gopro within the gimbal.
also, since i have been using both cameras at once as backup for each other, having them oriented the same way should get better results for each. using the overlap settings for the MAPIR, the GP will have well more overlap than is required due to it's fisheye. sometime too much overlap is not necessarily good, but at least it can be used, whereas too little is unusable.
haven't actually flown this way yet, was hoping to this weekend, but alas my real job is getting in the way...