Plastic fairing repair

I'm going to attempt some repairs on my NSR fairings. There's quite a bit of info on the subject floating around online, but it's hard to know what's going to give a quality result, and what's just a more of a cheap fix. I'm after any advice, or recommendations on plastic repairs from those who have done it before. I'd like to be able to do this at home with basic tools and equipment, i.e. heat gun, soldering iron etc.

Here's a few pics of the sort of damage there is.




It's obviously had some home repairs done on it before. Not sure if its some sort of plastic repair putty, or some melted plastic, but it isn't actually fused to the original plastic.

I once had the same problem with the valence panels on my '71 Chevy Vega. What I did is I used is an epoxy over the cracks and fiberglass/resin for the missing pieces (you can probably just use fiberglass resin for the cracks. I just used it cuz i had it laying around.). I beveled the cracks a little bit so that there was more surface area for the resin to adhere to. For the missing paces what I did, is on the back side of the panel I applied fiberglass and resin with saran wrap on the front so that I would have a semi decent surface on the front to work with. I sanded the high spots and finished with a little bit of bondo and a couple of hrs later you couldn't tell they were ever broken. If there are any holes thru the broken areas I'd would probably adhere a piece of sheet metal to the backside to strengthen that area. I don't know if this is the best way to do it but with care it can take care of the job and look good as well.

Sorry no pics of the Vega. Sold that years ago and don't have any pics to show a before and/or after.