The TP-Link HS105 wifi plugs work well and are also controllable remotely by app. I use one on my Tablo and one on my separately powered hard drive, which I find sometimes needs to be rebooted after a Tablo seizure.
There are even cheaper competitors out there but not sure about their quality/durability.
The only downside is that sometimes Tablo needs a real reset (pressing the blue button briefly) and power on/off won't do that. I too wish they would just build this remote functionality into the firmware, which I'm pretty sure they could. The risk of losing a recording or some other failure is less, in my view, than the frustration when someone is far away and the Tablo drops.
(In fact, I just had to do a remote power cycle at the same time I was writing this! The overnight guide download seems a particular moment of vulnerability for drops in my individual experience.)