The subframe looks nice done
I guess it should be either painted or powdercoated in colour of the main frame (should be either RAL 9006 or 9007).
By the way: your solution for the thermo unit is ways better than the solution the previous owner of my 2LA choosed:
20170429_190110 by
tomcatmj, auf Flickr
The PO destroyed the frame by this solution

but at least, i managed to get a complete frame including subframe and swing arm (in case i don't get the certificates for the given K&J swing arm and the seat) for a few bucks
In the meantime i changed the steering bar against a M-Bar...
2LA mit Magura M-Lenker by
tomcatmj, auf Flickr
2LA mit Magura M-Lenker by
tomcatmj, auf Flickr
Just a bit smaller, but at least with certificates for the german TÜV so that it should be possible to ride this 22mm steeringbar roadlegal instead of the welded(!) 1 inch Drag Bar.
I gues the previous owner liked to gamble withhis life, no other explanation for building such wanted breakpoints in a bike ike a welded bar and a selfmade rear-rising like the one on the following pics:
2LA mit Magura M-Lenker by
tomcatmj, auf Flickr
20170429_190224 by
tomcatmj, auf Flickr
Such modifications definitely have to be reverted before riding this bike ...but it will take some time to get the cash for the needed parts to restore this bike properly...at least some plans for optical styling had been done, viewable at
https://flic.kr/s/aHskqgfNUi in my mockup-gallery (all mockups done with "The GIMP" from
http://www.gimp.org )...