I like the OPs suggestion. I say simply place level restrictions on those areas, must be over level 60 to enter Dragon's Aery, must be over level 40 to enter Behe dominion, must be over level 60 to enter valley of sorrows - itll only affect some missions (people below that level shouldn't be doing anyway). That however wouldn't fix the bot issue because people still bot on their main characters too.
New claim idea for the 3 kings (Nidhogg/King Behemoth/Aspidochelone)? Just want to make things clear.
I'd rather just see HNM's claim their own bloody targets and have done with it.
Fafnir doesn't give a fuck about you bastards arguing who gets to fight him. That Tarutaru over there looks tasty, dinnertime commences. Just have HNM's randomly claim someone with a respectable (more than a Provoke+ in enmity) amount of initial hate, if they die drop to zero hate, and pick a new target and repeat the procedure.
Voila. Botproofed, and if you want to stand a bunch of level 1's around to "claim", they'll just get chomped and the HNM doesn't give a shit about your random Dias.
Well if the OP is looking for a new claim idea might aswell make an Einherjar LS.
There are lots of people in my old server and current one that haven't camped any of the 3 kings but wearing thier drops, M.body, E.body and such. Unless you desperatly want a D.Ring or a Ridill.