i can tell you right now
that they are NOT on 12" inch spacing aka centers
they maybe 16", but odds favor 24"
all the weight of any RV roof is on top
the structure is designed for weight pressing down,
not something hanging and swinging
you got to be sure the mounting plate spreads the force across the Top of the roof supports
pick your spot then mount a 3ft by 6ft or larger alu plate on the roof
the 6ft length runs the same way as the RV length
the 3ft width goes across the width of the RV
drill all the way thru so the bolts come thru the plate
fill the holes with dicor then push your bolts thru and tighten snug but NOT over tight, don't squeeze out all the dicor
seal all the mounting screws with dicor
use EternaBond tape sealer on the edges of the plate
it will never leak
