Some older sails like my 2001 aerotech charge 3.5m rig on a 400 mast because of the adjustment in the head cap. Really not much mast poking out the top. Foiling out if my car this fall I bring:
Two masts-400 and 430
One boom 135-195cm
3 sails- 3.5, 4.2 and 5.2
Two front wings
One board
Can foil in winds from 8-35kts.
Some overlap between sails and wings. Could add a 6m and be more powered up in 8-12 but 10-15 is lit on my 5.2. Keeping in mind I'm only 150lbs.
I hardly ever use my 4.2. Either on my 3.5 or 5.2. I personally think with foiling you only need 1m gap in between sails at most. At your weight you will probably get close to my high end range on your 4.0 since I'm a lot lighter. I also wish sail manufactures would allow more sails to rig on one mast just look at the naish chopper sails. Basically every sail rigs on a 370