Hi Shamirj,
In regards to the plastic wheel - they last a while, as long as you don't hit any sharp edges with them.. I know that from experience! 
In relation to your patch - I agree, I did a similar thing with a hole in my firewall. I made a plate from spare aluminium (an old floor panel) - I made sure though that there was plenty of space between the edge of the hole and the patch, as I didn't want to do the fix again.. I used bog on the top side - nobody has ever noticed.. I did think about doing 2 x plates (one on both sides) but worried about dirt/grime/water somehow getting in there, so only plated one side. Naturally I used pop rivets - to complete the Landy Look!
88 Perentie FFR - Club Rego
93 Discovery 1 200 Tdi - Club Rego
03 130 Td5 Single Cab
06 Discovery 3 Petrol
22 Defender 90 - Full rego
Bookmarks