Husbandry check request

This is Professor Obsidian. He's 6 months old and I've had him for almost two months. I converted a cabinet into an exclosure that is 37x18x48. Not ideal but it was what I had. His uvb is an arcadia 14% that is 20 inches from his highest basking spot. Basking light is halogen on a dimmer and runs 110-111 on slate tiles, taken with laser thermometer gun. Upper right quadrant is about 92-93, cool side is upper 70s to mid 80s.
I'd like to get the lower right quadrant into the upper 80s/low 90s. Ideas on hanging a safe light from the bottom of the upper basking platform?
Cool side is basically the bottom half.
He spends his time divided between the basking platform, running along the wood or eating on the bottom. He eats well, gets a variety of bugs (meals, supers, dubia, BSFL) 2x daily and greens (dandelion, turnip, mustard, arugula, kale) which he actually eats most of. He loves carrot and bell pepper but only 1-2x a week because it makes his poop runny. All dusted with rep cal every meal except Tues and Saturday dusted with herptivite.
When I got him in Oct he weighed 58g, today he is about 180g.
He seems healthy, he's active and eating. Is there anything I can do better?

Looks great! Since the enclosure is so tall, you might try building a second basking area with heat only on the lower level (similar to what you mentioned). Depending on the platform you might be able to mount a ceramic socket to the bottom of it, or perhaps you could run a heavy duty wire with a socket at the end along the corner of the enclosure and then wrap it to hang out over the lower area on one side. Similar to what Taterbug did with her tall enclosure https://sites.google.com/site/thelizardmadness/photogradient

Thank you, that link is great. The upper platform is 3/4" plywood so I could easily mount a small fixture under it. Just need to figure out what kind. I'd rather it be lower profile so it doesn't stick down too far so as to be accessible to Obsidian.