Just a quick question that I can't seem to find an answer to. I am doing a small roof mounted system on my RV. I am using Unistrut to mount to an existing frame that is adhered to the roof. I don't want to drill anymore holes in the roof. The Unistrut is Galvanized steel (I think), when finding hardware to use most of what I find in the store is Zinc but it says right above the zinc hardware "indoor use". I assume this is because it will rust? So I started looking for stainless steel that's when I noticed the price. One SS bolt was $3.76 and one zinc of same size was $0.47. I can't easily find aluminum that works with unistrut it all seems to fit Iron ridge or some other very expensive rail system. so my next question is should I look for galvanized? Is there any issue with using any of these types of hardware or even unistrut? I have spring nuts which are galvanized but I need the actual bolts to fit into the nut and they are not available at my local hardware store in anything other than Zinc or SS. Do I bite the bullet and go with SS or is there something else I should be using. I was planning on using antigaling lubricant as well.