I agree with all the above. I doc tails with rubber rings but dont castrate. As others have said the the earlier the better for both. I fing that even 12 hours after birth the lambs clearly feel the tightening of the rings on their tails though admittedly this sensation is brief.
Castration is tricky as both testicles may not have come down and if you dont know how to position the lamb and ensure both balls are in the ring you can easily end up with a "rigg" who is capable of reproducing.
I keep my ram lambs entire because....,
they are a docile, bidable breed
I can put them in with the adult rams when they reach puberty
They have the potential to be sold as breeding rams
I think they finish better
I slaughter them before 12 months so the testosterone does not effect the meat.
I realise that you have commercial crosses which will finish quicker than my sheep so you could keep them entire and butcher the males this year as they finish and run your ewe lambs on to next summer.
A couple of lengths of electric sheep netting, a leisure battery and an energiser would enable you to section off your grazing and hang on to the ram lambs post puberty.
Just a thought.........