Big snake experience comes from time. You get a baby and raise it from there handling each day getting use to it's growth as it goes. But you have to be informed of how there temperament could be, feeding response, husbandry needs, length, girth, weight. Experience comes in time but the knowledge of the species gets you the experience without making so many mistakes. Another thing to consider is how strong you are? You will not be able to out muscle the snake but you still need to be able to move something that is 100lbs or possibly more. I honestly dont think someone who isn't athletic or just simply out of shape should get a large constrictor, that includes red tails. Without the proper stability muscles in your body will make the snake feel very insecure during handling. That will create the snake to wrap tight to hold on.
I'm pretty sure all snakes keep growing through there entire life. BCI red tails can reach 10ft but 8ft is more common for females. BCC boas reach 12ft but 10ft is more common. Male burms stay similar in length to the BCC but have a faster growth and weigh more. The weight of the snake is really what makes it harder to handle. 50lbs moving compared to 100lbs moving makes a huge difference. Carpet pythons would be a good choice for a long medium build snake or even a super dwarf/mainland cross retic. Males stay under 10ft and females stay under 14ft.