>  According to the numbers just the fuel in the LM weighed 53,000lbs. I'm intimately familiar with delta-V, so big???Roughly 6380 gallons, which would require a tank 4ft high by 90ft long to store. I've touched the LM... it's maybe 15ft diameter.

Where are you seeing 53,000 lbs? 

Apollo by the Numbers has the total LM weight, not just fuel, at about 33,000 lbs ("Launch Vehicle/Spacecraft Key Facts" in the summary tables PDF).

The tables "LM Descent Stage Propellant Status" and "LM Ascent Stage Propellant Status" show, for example, Apollo 11 having 18,184 lbs of propellant (fuel + oxidizer) loaded in the descent stage and 5,238 lbs in the ascent stage. 

The descent stage kept its propellant in four cylindrical tanks -- two tanks of fuel and two of oxidizer. Descent stage fuel: 6,975 lbs, descent stage oxidizer: 11,209 lbs. 

[![Cutaway view of the arrangement of the Apollo LM ascent and descent stages. The ascent stage has two spherical propellant tanks in its "cheeks"; the descent stage has four upright cylindrical tanks surrounding the descent engine at the center of the stage.][1]][1]

The fuel is not very dense, 793 kg/m^3 -- sorry about the mixed units, but [Wolfram Alpha can handle it][2] -- yielding 1054 gallons. The oxidizer is denser, 1440 kg/m^3, [yielding 932 gallons.][3]

Four tanks, each 4 feet in diameter and about 6 feet in length, can store that volume, and the descent stage is in fact mostly fuel tanks. 

 




  [1]: https://i.sstatic.net/GFgv7.jpg
  [2]: https://www.wolframalpha.com/input?i=6975%20lbs%20%2F%20793%20kg%2Fm%5E3%20in%20gallons
  [3]: https://www.wolframalpha.com/input?i=11209%20lbs%20%2F%201440%20kg%2Fm%5E3%20in%20gallons