As I have pointed out in many threads of a similar topic Monarch Airlines successfully operated non-stop their A330-200 from Luton to Orlando Sanford back in the summers of 2000 and 2001 charted by Airtours Holidays, but stopped after Sept 11 bombings. During both summers these flights sold very well and no restrictions were imposed on the passenger numbers.
Since then the airline has refocused their Transatlantic services back out of Gatwick and Manchester.
Airtours back in 2002 operated their DC-10's non-stop on cruise flights to the Carbbiean, Miami and New Orleans.
Also this summer Britannia are operating a number of Cruise flights direct from Luton to New Orleans, Antigua and Barbados using their 763's.
Couple of weeks ago a "Business Airline" called fly
First annouced they were was going to operate a 752 daily service to Newark. Rumours of this seem to be fading now as they have failed to reach the deadline for funding the new venture. But questions were never raised about the runway length then.
The TBI Group which owns Luton has recognised the need for a full length Taxi Way, but at present the runway can cope with the current traffic levels and for sometime in the future based on current and future growth of aircraft movements at the airport. Unlike BAA which owns the other three major London airports the TBI group does not have bottomless pocket of tax payers money at its disposal
and their expansion stratagy at Luton is to extend the airport as required.
About a third of Luton's traffic is Biz/Private Jets and is quite rare for these aircraft to back track down the runway and just use the 5000-6000ft of remaining runway.
In the governments "white paper" they annouced aboiut future expansion of airports in the UK, the recommended Luton's runway be extended to 10,000ft but this will only occur when the need arises!
Extending the taxiway to the western end of the runway is going to be difficult anyway, this is where the main longstay car park is located and on quite a steep hill. The would mean the loss of a major car park for the airport which will need to be relocated and also levelling the land whick will cost millions. I think you would find the fire station would also have to be relocated.