Is there any way I can use one of the copper ports in the device as HA control port? I understand that there is a dedicated SPF port in the device for this purpose. Unfortunately the SFP that I have is 10G SPF+
you are forced to use the HA port. You can though use a RJ45 SFP if you don't want a fiber cable between the nodes.
More information which ports are destined for HA and which can be used for fabric-link can be found on this page:
So, there is no way to achieve a redundant control port in SRX1500?
Correct, you can only get a single control link connection on the SRX1500 platform.