Glad to be of help Oso.
Yes, covers strips should be 15mm wide for the biceps and forearms (7-8 mm each side) and 20mm (10mm each side) for the shins and thighs. Depending on how much thigh room you need, you can easily trim or shim the rear join depending on if you need less or more.
Also, if you intend to glue the joins on both halves of your forearms, you may need more than 7-8mm on each side to get your wrist through the end - no return edge on the wrist end of the forearms by the way. If you need the forearm wider at the wrist end, still trim the 'outside' join (the join facing out, away from your body) to be 15mm in total (7-8mm each side) but trim less off the 'inside' join and have a wider than 15mm cover strip. I found I had to glue both halves of the forearms (rather than use velcro like on the shins) just to keep the halves aligned due one half of each forearm being significantly more curved than the other.
C