Could buy a used cart? They are starting to come available now in the larger sizes.
If you are filling a big cart with 3 products through the same auger it takes a half hour to do this normally. Plus there is a lot of time spent at the bin filling trucks, especially with urea and any lumps or flowing issues. For me it made sense to go back to fall banding and just handle dry phos and seed in spring. Makes spring much more enjoyable for sure.
Really happy with current setup. Can apply other types of dry fertilizer with urea in fall through other compartments in tank, couldn't do that with NH3. Last 3 years I think I have bought my urea for same price per # as NH3 was in fall, and way safer. Stores in bin and can get it whenever I want, no supply issues in season. If you know what you are growing on each field may as well start preparation in fall.
Another thing to note is way less weight being transported with dry compared to liquid. NH3 is less again but in spring you have to deal with somebody else's tank usually that has crappy tires that create compaction.
AN ERROR DOESN'T BECOME A MISTAKE UNTIL YOU REFUSE TO CORRECT IT
Orlando A. Battista