I suspect the aerated blocks may be similar to the CMUs (concrete masonry units, what we think of as cinder blocks) over here. Always figured the were aerated for cost vs insulation, could be wrong.
Polaris connectors are another very common splice, but even uninsulated mechanical lugs or split bolts are even cheaper, and then wrapped with splicing tape and then electrical tape. As mentioned though, project from corrosion.
I've been in a relatively similar situation. For me, I'm trying to get the maximum amount of lift I can, so restricted this list more since the midrise options only get you about 4' total.
Full or mid rise scissors (ideal would be flush mount for minimal impact when down and open center when...
Can you order online and get it in time? Wire and cable your way is one online company with good prices per foot, but shipping will get you. If you can find it on Home Depot you'll pay more per foot but they'll ship for free. All this works great if your local shops won't sell by the foot...