The only part of your criteria that I don't think it would meet is being lockable, the end caps do up with zips.
Saddle bags keep the weight down low for better handling. Just be aware that a fully loaded top box may change the way the bike handles on twisty roads when cornering at speed and also low speed manoeuvres.
I have detachable bags but they aren't waterproof or lockable.
Looking forward to seeing a pic of your final setup KC.
The detachable tour pak rack was $215 from Harley Heaven.
I've ordered the Givi case and universal mount from the mob below. All up was $400 including delivery. I think they're in Germany. Givi stuff is much cheaper over in Europe.
Givi v47nn Tech:
Givi E251 mount:
I didn't get the cushion pad for the Givi box, I've heard some people say it pushes them forward. I'll see how I go without it.
Kc , looks perfect!
would they fit 03 sporty?
Will do steelo, I've ordered from overseas so will most likely be a few weeks.