If you go between the next set of rafters, why do you need elbows? Can you just move the evaporator over some? (I know that is easier said than done sometimes!!) I re-engineered my set up this year to get rid of the elbows. (I also went from a 6 to 8" pipe, put a new roof on and went straight up instead of out the window and up). If you can't move the evaporator, try a slight angle, gradually going from the evaporator and going to where ever it goes through the roof. Just a thought.
2017 - 20ish taps on buckets, boiling outside in two baking pans
2018-19 - 70+ taps, 14-buckets, 50+ on tubing, homemade arch from oil tank in my barn
2020 - less taps, short season, but RO kit was fantastic! Gained a maple cat!
2021-24 - expanded into the neighbors yards! 50 taps on buckets and 40 taps on tubing