Mmm. I think you will find that when the Luftwaffe started flying Ju8Ps over Southern England above 40,000 feet early in 1942 the RAF first deployed the Spitfire HFVI, which was a specially lightened Mk V with extended wingtips. Hampered, inevitably, by the Merlin 45, it couldn't cope. The planned upgrade - as for the standard fighter - was to be the Mk VIII, but the posh upgrades including retractable tailwheel took too long and I think the HFVII was next out of the box, with the very pointy wingtips first seen on the VI and a Merlin 61 forced into the Mk V airframe as for the Mk IX. It also featured a pointed tailfin which actually looks very nice and features on some restored aircraft.
http://upload.wikimedia.org/wikipedia/commons/b/be/Spitfire_VII_Langley_USA.jpg
The Mosquito was planned to have wingtips extended to some 65 feet but strength considerations limited it to just over 59 feet. The bomber (two-stage Merlins of course) was first out of development, intended to make use of OBOE at the maximum possible range - but de Havilland were asked to contribute to anti-Ju86P measures and in a week (!!) sawed the bomber nose off their high-altitude aircraft, installed the four-Browning one they'd previously sawed off an NFII to install one of the first dish antenna airborne radars, and MP469 became the first NFXV high altitude fighter. It and some slightly more refined production examples were given to 85 Squadron, then under John Cunningham, who took them up beyond 45,000 feet. A description of one of these flights is in CF Rawnsley's Night Fighter.
http://www.ww2aircraft.net/forum/album/watermark.php?file=5046&size=1
Unless I'm much mistaken the PR32 post-dates these shenanigans.
I'd love to see one of these delicate pointy beauties but right now I'd settle for any flying Mosquito variant in Britain! John