I suppose it depends how well you think you can control humidity and how much humidity is naturally in your household. For me, my humidity is around ~30 up to 40/50 on a rainy day so bumping up humidity to 50/60/70 is very feasible with my setups.
It's true the bigger height, the more you have to adjust, but PVCs are great for humidity in general and I found using an appropriate sized water bowl near the heat source help immensely with raising it. Then if it's too much you can move the water bowl further away.
I don't know what substrate you planned on using, but in my experience Reptichip is solid for humidity. You also have the option of misting once or twice a day on top of that, which an appropriate waterproof RHP will help as well with the moisture evaporating off it.
For your heating concerns, that also depends how hot you keep your room/ house. PVCs hold heat well so depending on the wattage of the RHP it could be enough for you not to worry about it. I keep my house around 65/70 so adding an appropriate heat source to an enclosure is very feasible to get desired temps. But you also can add a UTH along with the RHP if you feel the need to do so. Some just like using a standalone RHP.