Here is what Grant Whipp recommended for mounting gas springs:
"Most galley lids are 44-48" hinge-to-threshold, and here is the mounting that has worked for me for nearly 20 years:
Pivot point on the lid - 5" down the rib from the hinge
Pivot point on the wall - approx. 17-1/2" down the galley wall from the hinge, and in just enough to clear the lid framing.
I build a fairly light weight lid, and on a 4' wide teardrop I typically use 45-55# gas struts, 18 to 18-1/2" long in the open position. Most retail outfits will let you exchange for a heavier set if you need to.
One other thing to keep in mind if using gas struts is to keep the gas cylinder on the down side. When the seals fail (and they WILL fail), nasty fluid leaks out, and if that cylinder is on the up side, that fluid will run down the rod and drip all over your counter-top - better to keep the it contained on the prop as best as you can."
I've drawn this out and I hope Grant will confirm this is what he meant!
Grant's origonal post in full is
here.
Andrew