No disrespect to the fight to the end types; I salute your spirit. I myself, just gain no fun from being the last target standing in a 7-0 curbstomping, and I think I've exhausted all possible learning from that particular experience

I don't hope for the impossible wins anymore. It's not worth the 1 in a 100 hope, nor the repair costs. Now, close fights are still worth participating--even if you are simpy a distraction. I've circled many a weaponless 'mech as a distraction, or sent an ammo-less missile boat to draw off foes by a capture distraction.
I think it would be good to standardize a mercenary code of conduct. A quick term offerred in chat so a surrender can happen. Individual mechs have to offer to give, and by doing so they vow to move away from their base, shut down, and remain shut down. Powering up again makes them a fair target, and refusing to move out of their base or powerdown immediately after announcing they yield makes them a valid target.
I suggest typing "Yield" thats short, but to the point.
'Mechs that yield won't be targeted. They wont move. They wont start up. Violating that makes them a chump, and a fair target and not eligible for mercy even if they power down again.
Now, the risk is in yielding to a puggie who doesnt know this code, or is the type to shoot on a helpless foe..but then, if you are in a position where you have to yield, things aren't so great and you can't really make many demands.
I wish there were keybind chat binds, Could make one for premades stating "We accept surrender; type "yield" and power down outside of your base if you decide to give and we will not attack you." and broadcast it at the start of a fight.