You should be able to trim your hardware cloth cone to fit close enough to seal it with silicone.
I've only done one trap out, but it has occurred to me after looking at other peoples pictures that it might be easier use a piece of pipe like you would use to connect an observation hive to the outside. Attach it over the entrance and then give them a few days to get used to going in and out through the hose then put the cone over the end of the hose. It seems like this might make it a lot easier if the entrance is either high up or in an inconvenient spot.
You should try that and then tell me if it works
What ever you do make SURE they can't get back in.