If a spacecraft is too heavy to launch try sending the lander up dry. The fuel could be launched on a second LV.
Prior to either SLS or Constellation, NASA had tried (the term used loosely) to reexamine a lunar return on previous occasions. For the most part, it seems a combination of politics and lack of heavy lift doomed all these concepts. While the use of SLS is clearly in the air, it's potential as a HLV is great, enough that it made reexamining 2 schemes from the '90s plausible:FLO - First Lunar Outposthttp://www.nss.org/settlement/moon/FLO.htmlLooking like a mega-Altair with an Orion capsule, FLO was a large, single-vehicle direct lander. Weighing approximately 94 tonnes it would be impossible to launch without a HLV, and even the Block I form of SLS would be unable to hoist it. Later versions of SLS would be capable of launching such a lander, but obviously a second launch would be needed to provide a TLI booster.Something about this scheme struck me as promising, provided the mass could be trimmed while retaining its straight-forward nature. It doesn't take too much imagination to put an Orion in the capsule's place. Otherwise the only ungainly thing about it would be the extra-long walk down the double ladders.
The ELA design, while good, seemed to rely a bit on faith that modern composite materials could reduce the weight of the CM down to about 3 metric tons while still retaining the Apollo diameter of 4 meters. The Orion is deemed overweight partly because of it's relatively huge 5 meter diameter. Were it 4.5 meters in diameter and made largely of composites; maybe most of it's weight problems would vanish. ELA also was to use LOX/LH2 propulsion and maintain a single-stage configuration. Using hypergolics and a crasher stage might entail only having to use only a slightly more powerful EELV. Though it seems to me that a single-launch Falcon Heavy might get the ELA spacecraft to high lunar orbit where it could meet a pre-positioned crasher stage - placed there by another EELV - possibly an Atlas V-552. What payload could an Atlas V-552 place into high lunar orbit? About 8 metric tons? Enough for a small crasher stage with about 6 tons of propellant.Keeping that crasher stage as a hypergolic fueled stage, but the ELA ship as LOX/LH2 - would it all close, delta-vee wise? My math isn't good enough to work this out.