How do I install horizontal propane tanks in my Lance 1161?

I would look into building it out of 1" or 7/8" galvanized, half slotted uni-strut.

You could use 90* 4 hole L brackets with 3/8" cone, spring or strut nuts.

As you probably already are aware, you can purchase angle brackets also.

You could then bolt the rack right to the tray.

The tanks look to have mounting flanges which you could bolt to the strut.

T&B

Good luck and keep us posted on your progress.

Rick