I strongly recommend going with cardinal tetras instead of neons. Cardinals can handle the warmer temperatures that most rams need much better than neons, but have the same behavior and nearly the same coloring. Neons prefer things much cooler and typically are more prone to issues when kept in the 80F+ temps.
Also, the guppies may be hit or miss... If possible, try to get them from a breeder that has them in acidic and warm temperatures. Otherwise you may have high mortality rates if your strain is more used to alkaline & cooler temps. I never had any luck keeping guppies around long term with my rams for this exact reason. If you want an alternative, look at any of the smaller rainbows like Threadfin or any of the Psuedomugil family of rainbows. They're colorful, excellent dithers to help calm the rams, and have neat, eye-catching fin displays when the males are sparring or trying to attract a female
