Is there any point

Would there be room for staging about 3' high against the shed with cold frames on top? They could be used for hardening off stuff then cucumber, squash or melons? Someone clever could probably divert water from the shed roof to minimise watering. You could may be do the same in a greenhouse.

Depends what you were thinking of using it for. I don't think tomatoes would thrive planted near the ground in that situation.

Mark I have grown tomatoes in a shaded greenhouse I think heat is more important than sunlight