Thanks, he had quite a bit of red/rust color as a youngster. They go through a rather drastic ontogenetic color change as they age. I doubt many people would mind them keeping those green heads but they are striking in their adult colors too!
I've never fed outside the enclosure. I've never had a problem with food aggression either. I also don't just open the door and toss food in with them. When I feed it's usually the last thing I do after my normal routine. As an example, with a young animal I would have the food ready but go through spot cleaning, changing water, misting and all that before placing the food down as I leave. With an older animal I enter the enclosure, spot clean, clean out water, give the GU some attention, then leave the food on their food plate as I exit the enclosure. Another option for feeding in the enclosure would be to get the food set before your GU comes up for the day. Mine have all been late risers so this would be an easy way to separate food from keeper. I do like there to be some level of food association though, so personally I prefer the method I use. They are incredibly smart and I feel this bonds them closer to the owner. Just NEVER let your GU bully you into feeding before you're ready - slippery slope from what I've seen with other keeper's videos.
I'm always glad to see a new tegu owner, especially one who can do it right! Welcome to the club and enjoy.