If I were to try riding it, I'd first drill a stress relieving hole at the end of the tear, to remove the stress raiser and prevent propagation. I wouldn't fix anything permanently over the hole, assuming this is access to a spoke nipple, 'though you could try using a small Fiberfix patch above the damaged area, which you can probably lever back approximately flat. My main issue would be, if the rim is that hard to get a tyre on, any addition to the height of the rim bed will make it harder.
You'd also need to take a fine file/emery paper to the damage on the lip of the rim.