There are links to sites tied to diesel pickup truck enthusiast threads. There may be some in moho site threads. Mainly the experience of members with LPG component system vendors. There is less about any problems with combustion so modified (engine mechanical timing, injection timing, etc) as experience in time/miles is not well-defined in terms of climate, terrain, load and use; more anecdotal than is strictly reliable.
Much dates from 2008 when diesel prices skyrocketed. Less since then.
A couple I've saved:
Dieselbombers
Dieselplace: CNG (as reference)
DIY at Cumminsforum
Two vendors:
dieselperformanceproducts
Ecodiesel
My feeling about this has been (as above) that increased propane capacity has it's own benefits for an RV, and that
perhaps the use of LPG as a main fuel
extender while running the flats is a lowest risk proposition for a well-monitored engine.
.