We have way too much propane storage.
See it started off innocently enough. We had set a minor goal to not have the propane tank visible on the outside of the trailer. It was mostly aesthetics-related, and as such it wasn't a mission-critical item. Plenty of trailers have small, external propane tanks and that's perfectly fine. We looked at tank options. 11lb. tanks are really popular for this sort of trailer. We already have a few 20lb tanks at home, maybe those would work. We would have to fill a 30lb. tank less often. All sorts of things to consider, and then we looked at horizontally-mounted tanks and suddenly there were twice as many options. We worked up the layout drawings using a 30lb. tank footprint as a worst case scenario. We could install a smaller tank, no problem. After some fiddling, we got a 30lb. horizontal tank to fit under the bed. Then we moved it to the front of the trailer. Then back under the bed to a different location.
Once we were content with the layout, we got a tank on order. And immediately after, we decided to change the layout again. D'oh! "Well, that's okay, we can just return it and get something else." So we received the tank and I got to work organizing the return. No big deal, I've done this several times before. Got my return label and headed down to UPS to send it back.
"We can't ship that, sir."
"But you just shipped it to me..."
So that was a very interesting conversation. I'll save you the headache. I told Amazon the situation that I wanted to return the dang thing because it wouldn't work for us, but that I couldn't actually return it, so they told me to keep it and refunded me the full amount. At that point it became a no-brainer to just stick with what we had and make it work. Because, well, if it's free it's for me.
In order to get everything tucked neatly under the bed for a lower final height, we're using the water tank as a reference. The water tank is already situated and strapped in, so if we keep everything "shorter" than that, we're all set. So what that meant was we had to lower the propane tank a bit below the bottom of the frame. Since it is above and behind the axle, and only protrudes a couple inches, we're comfortable with it. It should be safe from impacts. But just in case, we built a rugged skid plate for it, which doubles as its mounting bracket. It will take a bit more work to take it out and get it filled, but the upside is that it shouldn't have to be filled very often. So it is in that way a blessing that we ended up with such a large tank.
I didn't want to use a through-bolt arrangement for mounting the skid plate to the trailer frame. The primary issue is that you have to use two tools; one to remove the bolt, the other to hold the nut (or vise versa). I could weld the nuts in place to alleviate that issue. But the other concern is that when the bolts are tightened, they will have a tendency to crush the crossmember tube. Probably not a visible amount, but it's not ideal to have the clamp load taken up by the tube like that. So I sleeved the mounting holes for 3/8" hardware. Then to prevent the load being take up by the welds that hold the sleeves in place, I stuck some nuts to some large diameter washers to help distribute the load in case the welds fail. Since we won't have access to the top side of the fasteners when it's all together, the nuts are welded in place. To fill the propane tank, we will remove the skid plate, then remove the tank. A little labor intensive, but it shouldn't be terrible.