Greenbeast sums it up quite well, thought the turnover amount was a bit less but its there if you take into account emergencies ect.
Sounds like you have a sound plan sell meet direct and keep profit margins up.
Looks like a few of us have same goal, i opted to go down the route of getting the bis into a good profit before even attempting any residential planning.
You will only get planning for a caravan for 3 years so if you were to apply now and you were given the opportunity of 3 years temporary permission for mobile home you would have to make that turnover in the 3 years fail and its game over.
Best route imo is build bis up without applying for residential permission, you are allowed to stay odd nights for welfare if its a genuine farming enterprise.
At kidding time you are allowed to stay on site in a temporary mobile home for the season which you have to remove after season is over.
You can use a existing building or a additional caravan for human shelter and occasional stays, be sure to record any conversations if you get a visit from planning dept.
They may try telling you you can not stay on site or have above but you can, but never mention residential use just its in connection with welfare incidents
My plans were stalled by council taking out a enforcement notice because my council would not allow any night time visits or any furniture.
At the enforcement appeal the planning inspector said it was exceptable for me to have kitchen units,sink,full size cooker,full size fridge freezer,table chairs,settee , boiler and radiators throughout the building.
Once you get to a decent turn over then get some advice and put in for temporary permission for mobile home for 3 years, that will give you another 3 years before you have to show full viability.
The council will get a planning agent to look over your plan and books before any permission and they will do best to throw obstacles in your way