i don't think you will be able to fit a metal fuel tank, they were type approved and fitting a non type approved fuel tank would void your insurance
the fuel cooler should be in the return so removing it over heat your fuel tank and wouldn't benefit you at start up when its needed
as SVO contains lots of fats and acids ...and fatty acids if you over heat it they will separate out leaving you with a thick white scum in your tank that will und up blocking your entire fuel system
this is the reason for the titration during production of bio-diesel to ascertain the amount of methanol/lye that you need to add to remove the fats and acids
and as for calm down... haha i'm not even dropping my smile
vegetable oil doesn't leave a thick white scum or every chip fryer in the world would have it sitting somewhere inside it, the reason for making it into bio diesel (titration) is to remove polymerizing agents which create a plastic type coating on cylinders etc and it's been found that by heating veg oil to certain temp or thinning it the effects of this are reduced dramatically as it changes the spray pattern and in turn gives you a better burn
thick white scum would only be caused by creating mayo or if you've got animal fats in it and since there shouldn't be any water or animal fats in the equation it shouldn't happen at all and if your opinion is true.... then it would block up the fuel system after the fuel heater unless by some magical way this doesnt happen with a fuel heater but does if it's hot in the tank?
(quote from journey to forever)
All oils are not the same. Some are 'drying' oils, such as linseed oil, which is why it's used in paints and varnishes. When it dries the oil irreversibly polymerises (polymerizes) into a tough, insoluble, plastic-like solid. At the high temperatures in diesel engines the process is accelerated. Steadily accumulating films of tough, insoluble, plastic-like solids are not what you want in your engine and injector pump
Polymerisation happens when the double bonds in unsaturated oil molecules are broken by oxygen from the air or water. The oil oxidises, forming peroxides (hydroperoxides), and the peroxides polymerise, bonding with carbon to create a long and stable molecule called a polymer (plastic). Another effect of oxidation is that the hydroperoxides attack elastomers, such as pump seals
Many homebrewers in the US think biodiesel shouldn't be used in the newer TDI or PDI diesel engines, because they think the high injection pressures will cause polymerisation. High pressures cannot cause polymerisation, only oxidation can do that.,
in short unless you have vast amounts of air circulating your fuel system (which i would hope there isn't!) you wouldn't have to worry about it, and if you're worries are towards your fuel tank getting lined with the stuff you'll notice it only happens when there is carbon introduced into the mix so using svo (not wvo) there shouldn't be an issue with having hot oil in a fuel tank hence why there are enormous companies dedicated to converting ordinary cars into two tank systems with the svo tank normally being heated and nothing going wrong
as for insurance that is a pathetic point.... purely for the fact an insurance company wouldn't even notice a metal fuel tank nor would anyone for that matter, you'd have more stick from an insurance company for adding a bloody air filter!!