Using fibreglass, newspaper, hiding it behind the plastic overs etc. might get you an MOT certificate, but you need to ask yourself whats going to happen to the car in the event of an accident. It might fold up like a tescos carrier bag, as the structure is weakened.
There is no way of knowing how weakened it has become unless the unfortunate happens.
I would suggest buying a MIG welder and learn how to use it. This is exactly what I did about a year ago with my old Merc. and it paid for itself the first time I used it.
There are plenty of youtube tutorials etc. to help. It isn't rocket science.
You don't need to be able to produce welds that look beautiful, just strong ones. As webby says " a grinder & paint can make a welder what he aint.

Don't go for the cheapest welder you can find, it will be difficult to use and cause much frustration. After seeking advice on here, I bought a Clark 135 TE, which is an excellent piece of kit.
I believe Webby was selling one a while back, not sure if he still has it.