RJ Endurance
My info is a bit dated and is based on TF33 engine burn rates. The F108s give about a 20%, or so, decrease in burn rate and more thrust.
Going off Mildenhall and using the overrun there for takeoff, we could put a good 8-9 hour sortie length on the mission. But, we never did as we always had a tanker top us off over the North Sea, prior to crossing Denmark on our way into the Baltic. Usual missions there were about 12-13 hours in duration, with all but 2.5 in the "operating area". We flew until the numbers crossing Bornholm island matched the flight plan fuel load to get us to EGUN with required overhead reserves.
Flying un-refueled out of Athens we would usually brakes release at 0700 and be back over the beach on final at 1530 local.