Re: Finally not so lonely!
You CAN weld aluminum with the proper type of welder, but you must use aluminum to fab the bracket if you wish to weld it. Cannot weld steel to aluminum.
You can use rubber, but I prefer better mounting myself as I dislike replacing rims.
Just make sure it WILL NOT MOVE whatever method you decide on.
And be careful bending that bracket on the frame. I've seen frames bend before the bracket does.
If more is better, then too much is just enough.
If you can't afford it, build it yourself.