I understand the need for "caution" as you are renting, but regardless of rail-mounted shed or ROR, both systems would require some sort of fixture to the ground for either the rails or the shed.
The amount of space required for each system is the same, but the ROR leaves your scope surrounded by a light shield, were as the RAS (roll away shed,
) leaves you exposed.
Both systems also require ventilation methods to 'stop your gear from cooking', you can't escape this with either system. But water from rain is a more serious consideration, IMO. A RAS may not be the best solution here? Unless you can raise the shed base to direct water away, and this entails laying a platform of cement to raise the shed, and the rails, maybe a ROR style shed with siliconed boarder might be a less dramatic alteration to a rented property.
Both ROR and RAS can be made relocatable.
Just a thought.