Didn't see any Rocketeer LoRAs ported to Pony, so I'm giving it a go. Trained on official material, various artwork, cosplay and some pics on Blender.
trigger words include "rocketeer helmet", "rocketer helmet_2" (for variations without the fin and modified varieties) and "rocketpack"
This LoRA is done in a way so that the helmet can be generated separately as some Rocketeer models seem to include the leather jacket and pilot pants in there even when not prompted.