I stripped it, then took the upper, lower, mantlet, barrel, wheels and rear panel to work to sand blast them. The finest / softest grit worked just fine on the sturdy HL plastic. Once sandblasted I filled in gaps and holes with fine putty, let it dry and sanded it all smooth:

After that was a base coat of dark sand yellow primer:

Looks more shiny than it was because I took the picture when the paint was still wet.
First layer of shading with a lighter color dunkelgelb, leaving the edges darker:

And a second layer of shading with an even lighter color dunkelgelb in the middle of the large surfaces:

I then spent some time trying to decide what camo pattern to put on. Finally decided on width-wise broad, jagged stripes of green, with brown borders.
First step: masking tape:

Green!

Not pictured: layer of shading with lighter green.
Masking tape removed:

Next step: adding soft-edge brown along the dunkelgelb / green borders. I'll see if I can find the time tomorrow, when there is proper light again.
Quite pleased with how it's turning out so far.