Thruxton fork preload adjustment

Spent a bit of time today setting up my new to me 2008 Thruxton. Adjusted the front brake and clutch lever positions, raised the gear change lever and softened the suspension.

What do folks use to adjust the front fork preload? I could just about access the nearside with a 10mm spanner but access to the offside is quite restricted even when slackening off and twisting the throttle control upwards. Ended up wrapping the adjuster in insulation tape and then using a 12mm ring spanner to make the adjustment.