Thanks to all who have responded, and sorry to have been slow to acknowledge all the great advice and opinions! For whatever reason my option to be notified of responses did not take, or I would have been more actively engaged. I will try to catch up, then share where I have decided to go :)
Vehicle is 2012 Silverado 1500 Crew Cab WT with a 5.3L, 6 speed auto 3.42 rear axle 4x4. Locking rear axle, HD trailering eqp. package. HD Cooling. GVW 7000. Towing guide for the 2012 says 9500 lbs. for 5th wheel as equipped, and 1712 maximum payload. I did add airbags w/ an onboard compressor, so leveling is easy for tow.
Trailer is 2108 Rockwood 2650WS. Pin weight is 1263. UVW is 7631 with CCC of 1632 making the total theoretical weight 9263. We tow with Grey and black tanks empty, generally Fresh water empty or close (I drain it after each trip) We also pack pretty light as generally we are only out for 4-5 days at a time max, and generally travel time is w/in a 2-3 hours (lots of Corps parks in that range for us)
I think that covers all the "whaddayagot" questions.
Like I said lots of great input, and even though there are some opinions/suggestions that appear to conflict, my call is you are all right. ( I should be in politics)
Swap to 6L would likely include computer, wiring harness, maybe transaxles (etc.) in addition to way more skills than I will ever have. Not to mention the costs and unanticipated costs. Do-able, but not reasonable to do.
Close enough to vehicle limits that plan B is pretty great idea, but not in immediate cards. Not really prepared to drop $50-60K this week.
Plan C looks like the way to go. Do some short term bolt on upgrades (cold air intake, tuned chip, dual exhaust) and squeeze some extra HP out of what I got, then move up to a 3/4 ton, maybe a 1 ton eventually when I find the right deal or my travel plans stretch out in retirement. 1 ton as I may go larger on the trailer (although this seems perfect for the bride and I for now) and I don't want to do this twice.
Thanks again for all the feedback, great community and very happy I stumbled on the group!