Ive ran the event in Stellarium and looks like we will see Siding spring as close as approx 1/3 degree from mars at 7/8pm before the pair sink into the abyss, though following it on stellarium, closest approach is arround 2-3am aest, with only approx 1/4 deg seperation during closest approach for other parts of the world under night skies at the time. not much in it really - unfortunately, this 1/3 - 1/4 degree seperation will not allow for any super long f/lgths, which would have been interesting, not complaining tho, - only a meter or two at most, depending on which direction the tail is pointing, ie, towards mars or away ?
Clear shkies & all the best to all who image/observe
looking on with interest,,,