Yes! This is required by NFPA 1192 Section 5.2.6 Ventilation of Compartments Containing Propane Containers.
I did not see such a drain when I was there, I looked through the compartment but missed it. And when Terry supplied my parts no drain was part of them. That's not a problem, I've a variety of drain fittings left over from last year's boatbuilding. And I have perfectly good lathe and milling machine I could make my own. I did see the ventilation in the door I got, of course, and that's installed already. Had to modifiy the installation due to the shell framework not fitting the compartment liner.
Could you put up a photo showing the drain?
Let's wander through NFPA 1192, in this case the proposed revised 2014 version, which I happened to trip over, the relevant section:
5.2.6 Ventilation of Compartments Containing Propane Containers.
5.2.6.1 Compartments shall be ventilated at or near the top and at the extreme bottom to facilitate
diffusion of vapors.
5.2.6.2 The compartment shall be ventilated with at least two vents, each having an aggregate free
area equal to at least 0.5 in.2 (323 mm2) for each 7 lb (102 mm2/kg) of the total propane fuel capacity
of the maximum number of the largest cylinders the compartment can hold.
5.2.6.3 If the lower vent is located in the access door or wall, the bottom edge of the vent shall be
flush with the floor level of the compartment.
12 First Draft Report: Proposed 2014 Edition NFPA 1192
5.2.6.4 The top vent shall be located in the access door or wall, with the bottom of the vent within
12 in. (305 mm) of the ceiling of the compartment.
5.2.6.5 Vents shall have an unrestricted discharge to the outside atmosphere.
5.2.6.6 Doors or panels providing access to valves shall not be equipped with locks or require
special tools to open.
Note this is not about water damage or water drainage at all. It's about ventilation of the compartment to the atmosphere. in the case of two 10 lb propane tanks, with is current with FWC that's roughly 2000 mm2 of vent area between the two vents. Flush with the floor level means the plastic structure of the compartment lining will have to have an opening at the floor, where the bottom of the 1" x 1" tubing of the aluminum structure now occupies. And unrestricted access to the outside atmosphere seems clear enough, a drain through the plywood floor then up against the truck bed, that's restricted, though it will drain water. Who needs structure? Well in another section they specify just how good the tank anchors, the door and so on have to be for structure.
I do agree with no lock, so you can get at the valves to turn them off in a emergency, maybe. And I do agree that propane compartments need ventilation to get rid of any leaking propane to the atmosphere.
Other bits in the document. No enclosed propane piping, not in walls, closed compartments and so on (some of that part sounds like the only approved piping location is on the exterior of the camper) until you start reading the rules concerning nearness to openings, fuel fills and so on. Probably a good percentage of FWC campers have heater exhausts or their air intakes too near to fuel fills or openings. And in this future world forget unvented heaters, not allowed.
Reading all the warning and other types of labels that will be required the smaller FWC campers won't need siding, you would not see the siding for the labels, and the inside walls nearly as bad. And here is the exact full text of one label about the required smoke detectors note not the only label connect with those detectors.
"Test smoke alarm operation after vehicle has been in storage, before each trip and at least once per week during use. May result in death or serious injury."
That's it, I don't think I'd do any testing with that advice. I am not looking for death or serious injury
Or how about this to keep you from breaking camp "Do not utilize this RV unless fully setup because a secondary means of escape is not available. May result in death or serious injury." Note their standards on size of door will rule out the door of most FWC as a means of escape, they have standards on what's a door, and mine does not meet the height requirement. And nearly every label they have in their huge supply includes the death or serious injury clause. Guess they expect us to not use RV's. More likely they have very limited experience of truck RV, especially those like the FWC.