Geez, so sorry you find yourself in this rough spot.   It's  very clear how much you love your pup and   focused  on  your pup's QUALITY.

Your situation  is doable.   As the Admin Guy said though, please get him evaluated  by a Certified Orthopedic  Surgeon and a Certified  Rehabilitation  Specialist.   If they think he is a good candidate,  that will certainly  help in your decision  making process.

While the scenario I have with my VERY ACTIVE front legger tripawd,  is not exactly  the same as with your pup, it may help.

I adopted Frankie as a tripawd, so don't  know the cause.  He's avout 70 lbs and, best guess, around six ish.   December 2018 he had cruciate  surgery repair on one of his remaining back legs.  He basically was a tripawd for the first coiple of weeks of recovery  as the other leg healed.  The sessions with the Rehab Specialist  and the techniques she used were invaluable  I'm his healing.  And healing he did!  Recovery was not easy though,, especially  if you are a one human household. 

Fast forward December  2019.  Yep, the other rear leg, same issue!  This  time I did the TPLO surgery (as opposed to the "fishing wire" one).  Back to trying to hop on two.  This surgery  was much "easier" and the recovery  time was quicker.  I did have some incredible help with my regular Vet as far as keeping  him several days until he was able to walk with very little, or no help.

I know this is such a different scenario and, as I typo,  I'm  not even sure why I shared it!  I do know that the TPLO surgery seems to be holding well (KNOCKING ON WOOD) and he is also very arthritic.  I give him joint supplements  and Rimadyl sometimes.  His "other" rear leg (the cruc6 fishing line one) is very arthritic and he has some hip dysplasia  as well.  KNOCKK G KN WOOD sone mpre, he is doing very well gets arpund  well, runs up and down the fence after whatever.  He does "self regulate" and saves his energy by laying down a lot, eating  laying down, etc.

Oh gosh, another dog jist came to mind!  A Lab named Murphy! IF I recall, he had hip replacement  surgery on his REMAINING rear leg  just six months  AFTER amp!!  It took a huge amount  of care and consistent  rehabilitation, but Murphy recovered  and became a very happy and healthy  dog after all the healing  took place!

STAY CONNECTED  and please know, we are here for you and COMPLETELY  SUPPORT YOU with any path you take.  You will make a decision out of love and that is always the right decision ❤❤❤

((((((((((((((((((((((HUGS)))))))))))))))))))))))

Sally  and Alumni Happy Hannah and Merry Myrtle and Frankie too!