45lbs @ 231/2". Think I have a hinge

23 and 1/2 inches draw length. It looks like there is a slight hinge on ghe bottom (right) limb just past the fades.

Hit a stone wall. aridity. serious lack of moisture in the air. Humidity as low as 26%. Highest was 51%.  LOL, draw length would decrease a couple inches every day @ 45lb.
Going to get a 4" diameter pvc pipe to keep a bow I am working on. Should be able to get and hold 50% in the tube.
Pic of braced bow and drawn to 22 @ 45lbs, which I believe to really be 28".

Thanks joe. I want to stain this bow with cherry stain and then put several coats of some kind of varnish to slow down the evaporation rate or to keep it from sucking up too much moisture (it's supposed to be going to Minnesota).
But first, I have to rehydrate it back to 9 or 10% moisture content. Hence the pvc with several little tobacco humidifiers.
I knew I was going to have trouble with aridity, but it has dropped sooner and faster than I expected. By May and most of June, it will drop to 10 and even 6%
Right now it is

The hydration chamber is a good idea. I'm convinced shifting MC is one of the biggest unseen causes of bow issues, at least in the long term. Hydration Chambers let you keep the bow at it's original performance easier.

You may have considered these options but in your part of the country hickory is king. It will shrug off all but the worst MC abuse and shoot all the faster for it. If you want to get really evil with your design you can do boo/hickory or sinew/tempered hickory (which will shrug off virtually all MC issues, or sinew/juniper etc. Boo/Osage will also be good. White Oak is also worth a shot. I've gotten away with murder with it. Avoid yew, red cedar and other such woods. Red oak is also sort of an iffy one in those conditions but that largely depends on the grade you get. I once found a dark red board of red oak that felt as least as dense and heavy as an Osage board of similar dimensions. Still kicking myself that I didn't buy it.

Do you have any other bows planned? It's hard to build just one. 

I've always leaned towards spar urathane. It's everywhere, comes in a spray can for even applications and with 7 or so thin coats does a good enough job. That and your pvc pipe should pretty much take care of issues. When in doubt just add a few more coats.

I've seen some people who will dilute heavy duty epoxy with acetone and use a disposable spray applicator. I imagine that creates a pretty heavy duty coat. Super glue is another that takes awhile but I've seen good results with it.

Lastly you might consider marine spar varnish. Ive not used it but it's an intriguing idea.