Hi,
you don't need to take the radiator out.
Without folding it too much, pull on the corner of the inner guard and bring it forward to give yourself a bit more room to get the spanner in beside the tower. Most Mokes have already had this done at some stage in their life so it will bend along the old previous line. On some of my own Mokes I have cut the lower part of that panel off like on the Export Mokes to make accessing the top arm pin, the brake lines and even the flywheel nut a lot easier.
The small bolt at the front is easy, just hold the head and undo the nut from the suspension side. Remove the large nut from the pin at the front and it gives you more access to the inside one.
I use a fairly flat ring 7/16, ones with an open end also tend to work best or my Kinchromes which have a shallow dog leg, and just undo it one flat at a time.
Terry