Make gold count as twice its caps value for Dialog Purchases.
Bases, Mercs, Professions, Cars, Doctor visits (healing, fixing crippling, radiation and poison curing), Rail Passes, Day Passes, Beer/Booze/Cigs/Nuka.
Maybe vary it from 1.5x to 6x, depending on the seller/trype of thing.
Also, Doctors and Bartenders will vend/barter for their regular inventory at full value of gold.