As above, fit with no washers. And don't tighten. Then add washers when your are doing the alignment. You can cut a chunk out of the washers, so that they are U shaped spacers instead. Saves you taking the bolt out ....
You could get in touch with the military vehicle trust. They're officially recognised by the DVLA as vehicle inspectors and can get you the registration. Costs about £200 for non members.