Yes, the lack of a fuel dump system was often a problem. We once spent hours burning off for what the AEO thought was a loose panel (it wasn't - just a bit of u/c door seal....).
But once the gear was down, the burn rate went up a fair bit. Can't remember the limit - around 210KIAS? But it nearly caught out at least one crew once. A bunch of old gits from the 27th Boat Spotters were out shadowing ships somewhere way north of civilisation once, when the captain noticed a possible hydraulic failure. "How long to get back to Scampton, Plotter?", he asked. A bit of mumbling and computer work from the back later, he was given the answer. "Multiply that by the burn rate, subtract it from the current total - yup, we'll still have Plan 2 fuel. OK, speed below (whatever it was), u/c down please, Co" Rumble, rumble, thump, "Down, 3 greens", came the response and off home they duly set. Then up piped the Nav Plotter "Why are we going so slowly, First?"........ It seems that his estimate was based upon the normal 0.84 cruise, not the actual speed they would be using with the gear down. They just made it to somewhere in northern Jockistan, it seems! The Nav Plotter claimed that no-one had ever told him that there was such a thing as a limiting speed with the gear down!