You are likely going the wrong direction if your goal is to be less tight on money. If anything, sell the '18 and look for something older you could pay cash for with the proceeds from the '18.
Anything in the used market is going to be tough still and you are not likely going to get favorable interest rates for something new, so you will be increasing monthly outgo making things even more tight. Early on in the vehicle shortage, you may could have done a favorable deal with the value of late-model used trucks being off the charts, but now it is largely offset by the increase in purchase price for the new vehicle with dealers not negotiating and even adding additional mark-up. None of this takes insurance into account either.
You may very well see an increase in insurance for a newer vehicle as well.
