Whilst I may have an 18.58, can't be too dissimilar. In the middle of building some myself,went with a 800mm long odd one on the kerb side for the Webber, and a 1.2m odd one on the road side for all our stuff, can't quite remember the measurements, but they add up to the width of the van. I built the drawers myself out of 40mm aluminium angle with additional angle on each corner for extra strength. Have laid a section of aluminium composite sheet inside the frame so it rests IN the angle, all held together with a strong adhesive type sikaflex. Have my heavy duty drawer runners, just need to assemble it all into the van. All painted up with Epoxy then 2-pack clear just coz. Drawers are light weight but seem quite strong, and will be further strengthened by the runners supporting them. Haven't taken any pics yet, but can do if you want some ideas.