The John Muir Way is an East Lothian Council initiative to link East Lothian to Edinburgh and the Scottish Borders. For the latest details on the project see http://www.eastlothian.gov.uk/info/1504/walking_cycling_and_horse_riding/821/walks_around_east_lothian/3.
A section of the John Muir Way between Aberlady and Longniddry Bents runs alongside the stretch of road known as the Aberlady Mile. The rather impressive stone wall boundary of the Gosford House estate borders one side of the road with Craigielaw and Kilspindie golf courses the other. As a consequence of the long straight road drivers do tend to put their foot down with the odd one or two (?) travelling above the speed limit. I would not recommend pulling in to the side on the A198 to attempt a cache and dash.
Either before or after the cache why not pop into the Scottish Birdwatchers Centre at Waterston House. It has regular exhibitions by wildlife artists and has panoramic views of the Aberlady Bay Local Nature Reserve. Entry is free and it is generally open from 10am-4pm except summer weekends where it is open from 12 noon to 6pm. See the website for complete opening times and details of the current exhibitions/shows.
An attempt on the cache wearing shorts should not be considered during the summer months unless you have a particularly high pain threshold. The cache is almost suitable for buggies - just the last 40 metres or so are not buggy-friendly.
GPS accuracy was not brilliant when I placed the cache however the clue should be good enough to cater for this.