Here are some links on GTP feeding, the abundance of such information pertaining to GTPs is why I made the suggestions I made. The meals may not be large for him, but he isn't adapted to eat rodents - on a regular basis at least, so something fatty like a jumbo mouse is a problem (lizards are generally very lean in fat), and rats are just simply too large and are fattier than a non-jumbo mouse.
https://www.tapatalk.com/groups/more...ts-t13966.html
Health Issues
Green Tree Python Husbandry
https://www.aruchondrofan.com/feeding-3-5
galangol (this one doesn't specifically pertain to a feeding regimen but may hold other useful information related to feeding and husbandry for you, since you mentioned this being your first GTP it's not information heavy though)
Some seem to say jumbos/rats in moderation are ok, but I certainly would not make it a staple.
Considering how disproportionately females are prone to health issues vs males, I would say sex-specific feeding could potentially be a factor. Many people will feed their females (snakes of any species) a lot heavier than they do males.
Keep in mind that behavior is not a basis around which you should determine feeding frequency or prey type/size. Just because they're on the hunt for more food doesn't necessarily mean they need more food. Breeding season may spark a heightened food response, but if you aren't breeding, there is no need in increasing food intake. Doing so will only lead to obesity. To the extent that it is possible, you should try to base your feeding regimen off of body tone. It isn't exact, but will yield you better health results than feeding simply because they're looking for food. Many snakes are opportunistic and would eat whenever you throw food at their face, whether they need it or not, because they don't always know how long food will remain available to them, even though in captivity it is plentiful.
Some keepers also seem to be under the impression that snakes can't get obese (no matter what species you're talking about). This is far from the truth, obesity is a very common ailment and a factor in death in captive reptiles, I would not personally knowingly feed my snakes in a way that has a high health risk. If you're careful about your approach, I'm sure you could make the rats and jumbo mice work, but obesity can be invisible until it's too late. Snakes unfortunately don't generally store fat under their skin like we do, so it can be very difficult to just look at a snake and tell if it's fit or overweight unless it's so morbidly obese it becomes obvious. Ultimately, it's up to you and what works with your animals, I merely offer words of caution.