Infrared heating is an excellent way to address this problem. You should be able to improve the finish quality and shorten dwell time as well. Unlike convection heating, it is very easy to zone the infrared heat to put more heat where it's needed and less where it's not. This can be done by positioning more emitters near the dense portion and/or by increasing the intensity of the emitters near the dense portion.
Using infrared to cure powder coatings on light/heavy gauge metal assemblies can be done with short, medium, or long wavelength infrared emitters. The members of the Infrared Equipment Division of IHEA, are equipped to evaluate your specific process and provide proposals for custom built ovens to efficiently cure your parts.