Well imo and just imo - best way to get cash flow is farming master chests thanks to TW farmers best targets are well known
FireToads, RottenGil (at LS beach) but you will need invite someone who not lvl 50 in group in order to green em up
RallosianBoncer, Headhunter, Aflictioner (sp) (bigger one) - lower lvl mobs that tend to drop a lot master chest
If you have group I'd highly recomend farm Efreety Bastion to bad this zone on 18 hour timer. SOF is good choice also 2 named take around 2 min to kill Overlord but if you also want to kill Fright you got clean upper floor so it might take upward 20min... Menagrie and Icespier summit kinda waste of efforts imo
Btw for harvesting collectible best place isnt ROV its Obelisk