Move the tank upstairs, or heat the basement.
A RHP provides an excellent hotspot and has the added benefit of raising your cage temps. Set the probe under it for 90 degrees and the rest of the cage will warm a bit too. The middle will be a bit higher than ambient and end farthest from the RHP will be skosh above ambient.
A UTH will provide only a hotspot and do little for the ambient temp.
In my cages, the only thing I use are RHPs.