Please can we have some better farms

The main thing I want is the rare spawns to be 100% chance to spawn not the 30% that it is right now. The second is i would like is alt farms for weapons tide to wave based bosses such as the Maggie and the Lyuda on Tremendous Rex.
If this can be fixed some farms will be tones better with out spending hours on a farm that is 50% of the time a load screen or down time