Yarbles,
No, the doors are not removed. The B.Mk IV Special, B.Mk IX Special and all B.Mk XVIs had a bulged bomb bay to accomodate the 'cookie'. Mosquitos without the bulged bomb bay could not carry a 'cookie'.
Most low alt Mossie raids were done by armed FB.Mk VIs, the ones we already have in AH. Why? They were tuned for low alt performance whereas the bomber and PR mossies were tune for high alt performance. For example, the B.Mk XVI hits those high speeds at 27,000ft, but on the deck it could probably not exceed 330mph. The 424mph NF.Mk 30 could only do 321mph on the deck, slower than our flame dampened FB.VI by 17mph.