I do not mean to rain on anyones parade. But, there is a potential problem using single pole starter relays in this circuit.
If the relays with suppression diodes drop out slower than they pull in, you could have an overlap situation where both k1 and k2 for instance are closed at the same time.
This could cause a very high current pulse which would blow the fuse and could weld the contacts on the relays.
This would only happen if someone were to flip the control switch quickly from cover on to cover off or vice versa without a pause in the center off position.
The easiest way around this would be to use a switch that forces you to release pressure on the lever while in the center off position before it will allow you to proceed to the other position.
Such switches are made. Unfortunately, I don't remember who makes them or who sells them.
The timing of the particular relays that you use may not present this problem. But, it is something to check before turning the system over to the user.
Ron