I can speak to this as I have tried a few options. I originally tried the dremel and used the mount from markusgri on thingiverse (link below).

https://www.thingiverse.com/thing:3938914

The mount is good but you will want to design a spacer to sit between the stock z motor mount the the aluminum extrusion to support the carriage and prevent torsion. I can take some pictures of my setup if this doesn't make sense. As far as heat, I never noticed an issue although I would print in a higher temp/creep resistance material like ABS/ASA/PC to reduce the likelihood of an issue.

When trying to cut aluminum, I found the mount to be insufficiently rigid even when printed in polycarbonate with 100% infill. I ended up getting the following mount with a 500W spindle.

https://www.amazon.com/gp/product/B08SC9K538/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&th=1

This new configuration is quite a bit more rigid (at the expense of much higher cost obviously). You will still want to print a spacer to take up the gap between the linear rods and the aluminum extrusion (I have an STL for this one) to prevent the rods from flexing under torsion. I can confirm that this setup will cut aluminum cleanly althougth I am still trying to dial it all in.