You should probably get yourself a shorter speargun.
I often spear in poor visibility. For GB we generally recommend euro/pipe, band- powered spearguns 75-90cm - that's the length of the barrel pipe. As a rule of thumb, the shorter lengths are more appropriate/necessary the further east you go (e.g. shorter for Sussex, longer for Cornwall).
I started spearing with a 90 but for Dorset it was usually too long and heavy for the limited visibility and fast moving fish I often encountered. Switching to a lightweight 75 helped a lot.
75 is a pretty good general purpose size for the UK (as is 80/85/90) but sometimes 75cm is still too long for the visibility available. It could be argued that it is not worth spearing in such poor conditions but, if you're there, with your gear, might as well try! I recently bought a 60cm speargun for such conditions.
Even the 60 may be too long for some conditions. In which case something very short, like a 50cm band-gun or pneumatic (a 50cm pneumatic is usually significantly shorter than a 50cm band-gun) might be the way to go. Small rollerguns are now more common. There is very nice looking Greek 55cm inverted roller speargun, also the Turkish company Apnea produce a wide range of sizes, including 35cm and 45 cm Whaler roller spearguns. I had the opportunity to see and hold one of 35 or 45 roller spearguns recently and was reassured to see that it looks and feels like a good, real, proper speargun. An alternative to a short pneumatic perhaps?
I believe RA will make spearguns down to 50cm to order. I know of several spearos using 70cm railguns in the UK in poor viz and on wrecks. And I recall a US spearo using a 50cm railgun to hunt ling. No doubt a 60cm speargun could be ordered if required. RA railguns are heavy duty and can handle the biggest fish if necessary. The 1x16mm Sparid (or cheaper rail-less Scorpia) is a good option but, as an American you will likely prefer the 2x16mm Tuna model - more power!
There is also a carbon barrel version and, I think, now a 2-band rail-less model (possibly 2x14mm). For such short guns a rail is unnecessary mass ( inertia) and causes extra lateral drag IMHO.