70 340 4-speed dart - talk me off the ledge

ok, to update i have been clearing out the garage to make room to work on this, so pics from on the trailer will have to do for now,

as you can see the drivers side is pretty roached. both look patch-able as the rot is limted to the lower portion of the front rails and the t-bar cross members. looks like there is enought at the top of the rails that is solid to patch into.

anyone's thoughts on the auto rust tech's frame rail caps? they look like will be the quickest way vs. full rail replacement.

drivers side:
20161008_001617_zpsivvujnku.jpg

20161008_001656_zpsehdwzsjl.jpg

passenger side:
20161007_193324_zpsacw78dgb.jpg

20161007_193312_zps5kgvwzv1.jpg