Before any "crush or shear strength" is important in this installation you would have to crash the airplane into a canyon/stone wall, in which case it is a moot point. Obviously neither the developer of the STC nor the approving FAA engineering group nor Cessna, who never doubled up this area, don't have the same opinion as minton on this point.
(In fairness to minton, I too put off making this mod for some time out of concern for maintaining structural integrity, expecially on a tail-dragger. It took me quite a while and many consultations with people familiar with aircraft structures before I was comfortable in doing this. Cleo Bickford, former club HIstorian and aircraft manufacturing engineer with Anderson-Greenwood (last owner of the Bellanca type cert.) is who convinced me that my concerns were without basis, and that the Del Air STC was fully adequate to maintain structural integrity of this airplane. I'm not trying to diminish what I believe is minton's conservative approach on this. I'm only saying... there's a lot of qualified folks who don't think extra structure in this particular installation is necessary, and adds unecessary weight and complexity.
It looks to me like the photos of the bag door you are considering will have all the necessary parts for this mod. Just be certain to get a good portion of that aft bulkhead in the pic.
Pete, I suggest you get a copy of the Del-Air instructions for study by you/your installer before going much farther with this. I'll try to post them in the Mx Library. (Remember, you'll still need to obtain your own assigned/serial numbered copy from Harry Hellicker.)
Look again at the other link to the post showing Del holding my salvage door and the finished product, then....
... here's some pics of mine (performed by Del) which should give your some more help in decisionmaking:
Del, (aka: "wingnut") holding my salvaged door, as-removed:
Here's the door after the excess old fuselage was removed from it, and it was stripped of paint:
Here's the framework:
Using heavy paper, trace the door outline to make a stencil, then transfer it to the fuselage with a felt-tip pen:
Remove the interior to gain access to the sidewall:
Then, with great courage...make the first cut to remove the sidewall.
(Seriously...the STC covers this quite well.)
Heres the area (with carpet removed) cut away at the floor-line to accomodate the door-frame.
Paint the finished door to match the rest:
Happy owner...who can now access all the junk he carries in the bag compartment (notice the spring-stut added at the top of the door:
And a finesse' of final touche'.... use a sailboat companionway door-strut ($11 at marine stores, or expensive Beech STC'd unit for $80) to hold your door open in a breeze:
Here's how it looks used on Barons...but the same spring can be found at marine suppliers:
Is that the interior reinforcement that surrounds the door opening? Or is it something else that I need to ensure is part of the deal?
I believe that there are many threads addressing that issue to reference with the clubs data base.