Outer Limits 4x4 Board

My new injectors from HiFlo arrived today. Ended up aborting the fitting operation due to not having a suitable tool to hold the injector while trying to undo the very tight nuts on top of the spill tube banjo fittings.
Trying to undo the nut was resulting in the injecter trying to unscrew from the head which was clearly going to break the fragile looking spill tube. Tried holding the center part of the injector with a (good quality) 19mm spanner but it rounds off the injector body. Seems like the only way will be to hold the 22mm hex at the base of the injector but unfortuately I didnt have a 22mm open ender. Even if I did, its going to be e a tight fit.
Am I going about this the right way - is there a particular type of 22mm open ender which works best?
Also thought about holding the injector body with the 19mm spanner or vise grips and using a rattle gun on the spill tube nut, but so far I've I chickened out on this option.

Suggestions from those who've dealt with this before would be much appreciated.

Nissan probably make a special tool for it, But I have made a spanner to fit in there for most of them (19mm)
Basically need to bend the spanner up at around 60deg to get it in there and shave some of the outside faces..

The return rails are about $60 from memory, some of the injectors are alot harder to get into than others so it really comes down to how patient you are.

maybe a 19mm or 22mm pipe spanner

i juggled a 19 and 22 in there, got all of them undone till the last one...snapped the return tube cant remember how much but had a replacement 2 days later from nizzbits.

Tried the rattle gun while holing the body with the 19mm spanner. Result - one broken spill tube....

It happens. At least they arent expensive.