Chidoc. If the GSA from Eastern is not transferable, an amended of the GSA doc to include will do. No need to start from scratch & it may not be granted in the first attempted. Every agency allows the current cert to amend to add new version & resubmit. This should be the way to go if it's not transferable.
Chidoc one avenue that you may investigate is road traffic management. I have seen similar products to the guard lite on the roads here in Ireland for the past 10 years+.
These are used for power to traffic signs, warnings, stops signs, traffic counts, road weather monitoring systems etc in the countryside. They would be in use by the thousand.