Re: A true chemical free
100% chemical free may be difficult (if you include feed in the chemical category).
I am treatment free (starting year 3), the only thing I have used is sugar feed. Most of my hives would have not made it the first year without it. However my season will be much shorter than yours and if the weather doesn't cooperate it can be ugly getting hives to start. I do not see the point in starving bees if the cause is out of their control.
With that caveat getting the bees a good start, selecting good genetics and some people believe small cell seems to be the basis for going treatment free. I personally have a mix of foundation and natural comb, and am moving into all natural comb and trying small cell in the center of the brood nest this year. So far I have only lost one hive, and that was due to a late summer queen failure. I should have combined the hive but tried to get them the raise their own queen. It did not work.
"What we obtain too cheap, we esteem too lightly: it is dearness only that gives every thing its value." Thomas Paine