Re- finish, I use glass cloth and epoxy resin followed by light coat of two pack auto primer prior to laying out panel lines with ruler and pencil. Of course it goes without saying the preparation time during this phase is a little time consuming, same as any decent paint finish I reckon, lots of sanding using progressively finer grades of paper upto 1500 wet and dry. You should end up with a shiney scratch free base surface prior to drawing on panel lines as the guide prior to application of metal tape... Flite Metal offer larger width self adheasive aluminum if the duct tape is not wide enough. On the MT-P51 and many similar scale warbirds the wide aluminium duct tape should do the trick though. On the wings that will be paint finished, where the panel lines are marked out in pencil I use a fine jewlers file edge and gently go over pencil line to create the panel lines in the primer. Its important to use a quality two pack primer, you can get this from auto paint suppliers, brands names vary regionally so just tell your local 'expert' paint guy that you want to paint over epoxy fiberglass as this once cured sands easy without clogging paper fills scratches etc and also will not lift during later top coat and insignia masking....
Oh yeah one important last paint tip Iam using a low pressure/high volume auto spray touch up gun and air compressor, approx 30 psi max for spraying, you should let your paint guy what gear you painting with ideally, so he supplies the right paint weather primers or colour top coat. I also use Humbrol hobby enamels and airbrush for weathering which go over auto primer well. Leave clear coat till last as flats are easier to spray and cover better. If you want a gloss or matt finish apply last in 3-4 fine dust coats.... easy eh! ; )

If I recall correctly AUW was 10.5 lb for my Ridge Runner with the glassed, metal finish and Y.S. 91 fitted... you would have to be pretty heavy handed with the glass and paint to be over 11 lb AUW and thats well within reason considering model size and wing area for the MT - P51.

Cheers- Marty