my thoughts are:
-use a metal heat shield on the pipes attached with chose clamps or tacked on, leave a small air gap between the pipe and the shield
-use a metal heat shield between the pipes and the tank with reflective material attached to the pipe side of the shield and insulation on the fuel tank side of things
-try to run some of those fuel lines and electrical a different way so they simply don't run past the heat source. possibly straight out the front of the tank and then over to the frame, shielded as req.
-wrap the pipes with header tape to keep some of the heat away from the area
I think you have a heat source right next to the fuel storage/source, fuel pump, fuel lines and some electrical. it will, at least, be heating up your fuel so less molecules per cubic inch for your power ratio (racers try to run the fuel as cool as possible for that reason, right? remember the fuel cool cans with ice) . you could run the fuel and electrical over the tank and out the front side of the tank, between the pipes, and that would help especially with some heat shielding and some retainers for the lines so they don't rub. you could install a reflective heat shield with some non flammable insulation (between the tank and the shield) and that would help. google reflective heat shield for automotive and see what comes up. some eg below. something is better than nothing. I am a professional firefighter so I always see them "after they fail" and the vehicle is reduced to a shell. wouldn't wanna see that happen. so many times guys spend money on the big ticket items but some of the other important stuff gets missed. that would be a shame. even some hot water tank wrap from home depot would work but there are so many great things on the market these days. why go minimal on something that has that much potential to cause problems and delete you investment and hard work. if you look under a modern vehicle there is usually some fairly flexible aluminum heat shielding. maybe a trip to a pick n pull would yield something useful that could be cleaned up and used. I would def reroute the fuel lines and electrical anyway. heat breaks things down and causes premature failure. it also softens things and allows them to take form so things like exhaust hangers will likely have a little more "give" after awhile and could allow some sag in the system. this could mean that inch will become less over time and with use. if a hanger were to fail the pipe could actually be sitting on a fuel line. the other thing to think about is the ride height of the truck. a low truck equals less air under the truck to allow air flow to cool things off when the truck is sitting still or moving slow. what will happen when the truck flexes over a curb or bump etc?
take a look below at some of the links, the youtube one shows some good looking products and there are others in the background that look great too. a bit of that style of product also makes the build look professional and like a lot of thought went into the design.
end of rant, sorry.
https://designengineering.com/produc...ds-reflectors/
https://www.amazon.ca/DEI-010129-Tit...03913138&psc=1
https://www.youtube.com/watch?v=E-hK8r1Ldgg
https://www.heatshieldproducts.com/a...ermal-barriers