Per Dexter Axle, the bolt holes of their # K71-724-02 Torflex Axle Lift Kit are right at 9 inches apart on center. The # K71-707-02 would be better choice as the holes are right at 8 inches, if the 1/4 inch less lift would work for you.
The # K71-707-02 kit is compatible with #10 Torflex axles with 2,300 to 4,000-lb capacities. view full answer...
I think what you are meaning by "centerline" is a 16 foot measurement as taken from the center of the mounting arm to the center of the opposed mounting arm. The Solera 18V Power RV Awning, 16' Wide, # LC729486 requires 69" of open vertical space on the wall of your RV for installation; this is measured from awning rail straight down and needed for installation of wall-mounted brackets. The canopy fabric, when fully extended, is 15' 1" wide x 8' long.
An awning rail # LC715217 is needed... view full answer...
Weight distribution systems are recommended based on tongue weight which is typically 10% - 15% of the trailer's total weight. This would put your tongue weight somewhere between 800 lbs and 1,200 lbs. 777 lbs seems awful low but I have a system that will cover that entire range for your Surveyor 295QBLE travel trailer. I recommend the Equal-i-zer Weight Distribution System w/ 4-Point Sway Control item # EQ37120ET.
This system has built in 4-point sway control that will keep your trailer... view full answer...