Sorry Josh,
If you take two boats of equal SA/D (sail area to displacement) ratios and equal D/L (displacement to waterline length) ratios, the bigger boat will always be faster in all conditions, light or heavy. In light air the taller
rig of the larger boat operates higher in the gradient wind range and in heavier air the longer waterline and greater stability of the larger boat means that it will have greater speed.
If you look at PHRF ratings you will see that in a general sense as boats of similar sail area and weight ratios get bigger they get faster.
I think that your error may be derived from comparing light displacement smaller boats to relatively heavier displacement larger boats. But when you talk about a small boat carrying all of the gear and consumables that is required for longer passages, the smaller boat will by necessity have a substantially heavier L/D ratio and substantially less sail area in relation to its displacement and so be significantly slower. This occurs in a couple ways but as a simplification, while the sails and gear needed by the boat is in proportion to the size of the boat, the amount of food and water per person and tools needed to maintain the boat are the same whether the boat is large or small. Further compounding the problem, given that small boats really are slower, they actually need to carry more food and water per person than would be required on a larger boat making the same passage.
With all due respect, I suggest that you really do need to spend more time on the water and do a little more reading.
Respectfully,
Jeff