I want to take pictures of planets, well at least Mars, Jupiter and Saturn with some surface details. I have a Canon EOS 7D Mark-II and a Tameron 150 - 600mm lens (very heavy), a 1.7X extender, and a... meh... half decent tripod that can take a peak in the sky directly overhead, with some neck discomfort. So far, I have been able to only capture a fuzzy blob of Mars with aura of orangish red light around it. But that is partly because the skies were not very clear, and some clouds quickly tried to hide the sky when they saw me taking a picture. And it is Late October. So... Any suggestions, ideas,
a 1.7X extender
By 1.7X extender I think you mean a Teleconverter; a projection lens that re-images your main lens's focal plane back on to the sensor, but magnified.
a Tameron 150 - 600mm lens (very heavy),
This says Tamron SP 150-600mm f/5-6.3."
So 600 mm x 1.7 = 1020 mm focal length, and I'm guessing f6.3 at 600 mm so 95 mm aperture.
This combination is a f=1020 mm f/10.7 telescope!
If you magnify the planets they will get dim at f/10.7 so you'll have to expose longer, meaning atmospheric seeing will cause some trouble.
From here I see that
Canon 7D Mark II comes with a 22.4 x 15 mm CMOS sensor, which has a diagonal of 26.96 mm (1.06") and a surface area of 336.00 mm²... The sensor has a surface area of 336 mm². There are approx. 20,200,000 photosites (pixels) on this area. Pixel pitch, which is a measure of the distance between pixels, is 4.08 µm.
So with f = 1020 mm and 4.08 E-03 mm pixels, each pixel will be about 0.83 arc seconds.
You are ready to go, and you should probably skip the teleconverter at first and just gain some experience; setting up, avoiding dew, pointing at the planets, watching them drift by as the Earth rotates, then re-pointing over and over.
Then taking photos without vibrating the whole thing! DSLR's usually (always?) have mirrors that flip, you may want to delay the exposure until it stops vibrating.
Then taking many photos and learning to stack them, or sort them for lucky imaging.
Photography SE has lots of astrophotography questions and answers I recommend you go there and read a bunch before asking further so as not to ask a duplicate question.