Looks good Lee but how it that any less of a mod than bolting a cage into the floor...?
When a water tank it bolted in, it is classed as being permanently fitted so only a few companies will provide insurance at what is now (for me) a massively over inflated price, for me to insure the van with the tank bolted in, my premium is double, £800.
Fitting eye bolts is an acceptable modification for any insurance company just like installing racking, you just tell the insurance company that you have done it and the don't really care and don't increase the premium.
Strapping the tank to the eye bolts is classed as carriage of own goods, the van is not over weight, and is like carrying any other load, like going to bq and having a pallet of bricks put in the back of your van.
So is insured, the insurance know there are eye bolts fitted, and I am carrying my own goods without being screwed and I'm confident that they are a hell of a lot stronger than the manufacturers tie down points, and just as safe as a bolted in tank.