Cargo Door Installation Advice

[Skywalker]

Hello Guys
as my plane ;N88TN is still under few upgrades and annual inspections in Canada, i am considering about Cargo door modification, as it seems the pain in the neck kind of thing to put 110 liters of ;normal suit cases; thru the main door and to the back seats,( although i never did this ) the price of this mod with installation is huge, 25K USD (for P model ); does any one has done this mod on P Model ?,will highly appreciate the advise, and feed back.
Also other pilots Inputs about loading and unloading the suitcases in C337 ,is it really hard to get the stuff loaded/unloaded thru main door, ? , i did read some discussion about the Cargo Door and where RT owner Roy ,is defending the soundness of his installation, and tests performed to ensure the integrity and safety of the installation , but for me its still a major alteration of the airframe and another point of failure which will be added into the airframe??
pls advise,
Regards
Dennis