Be aware that you can relocate that Caterpillar secondary filter to any location you like. All you need is to remount it and get longer hoses. You leave it after the lift pump, as it is now, but it's physical location is up to you (or a lazy coach maker who did not relocate it.
Our current and last coach both had the same Caterpillar secondary fuel filter, but both had a manual primer pump (which is easy to add-- just replace the block off plate held by two bolts) AND it was located where it was easily serviceable from the side of the coach.