Thanks Blackwolf.
Yes, for most shots I'm coupling the 105 with an extension tube. Sometimes a 12mm, sometimes the 20mm. On occasion I'll add more than one, maybe all 3. For these shots, I had a single 20mm on.
As for getting really close up, firstly, the dragonfly's head isn't as small as you might think so at 1:1, it can be filling the frame nicely. As I'm using the 20mm tube, it permits me to pull back a bit on the extra magnification having the ring on gives me, kinda back to where 1:1 is roughly but so I can shoot a little further away. Gives me more DoF, more chance of a sharper result.
Then, with subtle cropping using the resample option and decent sharpening and noise reduction, I can get the results above. It's just a shame the sunlight was so bright coming from my right.