mebe some angle under the mesh for better support.. Have you figured out your consumption rate? I have a 30# horizontal, after 4 days in April running the Wave + Propex all the time I only used ~25%, which would give me ~2 weeks in spring/fall which is what I was shooting for.. my trailer's pretty big to heat, that might be far more than you really need weight wise? Fill it up, go out for a torture test weekend and use as much LP as you possibly can, then come back and refill it and figure out how much you used.. you can also use a scale and figure it out yourself.
there is 11# vertical and 5# vertical which are rather short, and much lighter if they are more suited for your M416.. these can often be mounted really anywhere you can come up with so it can relieve alot of tongue weight.