For a 5nm join, you wouldn't intercept gp until 3nm. Initial airline feedback was that it would be too close. b) There needs to be a nav mode change from rnav to loc at only 5nm out. Again this was argued to be too close. I think it would work, but it would involve an amount of training and trial
Yes, 5nm is too close. Only a minor hiccup capturing the LLZ will prevent GS capture and the whole approach rapidly turns to worms. Besides, you can't descend below the local MSA (at least 1500ft? coming in over the water towards terrain) until you've captured the LLZ; you'd be above the GS by then.