Tank Size and insides for HOG Island Boa

Hey so I have a male Hog Island Boa and I wanna build (cuz its likely cheaper than buying pre-made) a tank for him and he isnt full grown yet but I would like the tank to be big enough for him when full grown. The tank I was considering building would be 40"(3ft 4in) width by 18" depth by 31" tall wondering if that would be big enough for an adult. Also wondering what type of wood they prefer to climb on, I have a cleaned piece of drift wood in his tank now but he doesnt seem to climb to much on it so wondering if its an issue with size or thickness of the branch or the type of wood. ANY help/advice is greatly appreciated :)