Howdy from Dallas!
If you are using the heavy wide chain, you can probably get away without using a tensioner. The lighter chains have to be more snug to prevent derailing, so they telegraph chain slap and engine vibration to the rear dropout, and can make your feet numb!
See my user pics for my case mounted idler wheel.
I also have ideas for using an idler wheel from the tractor company, mounted between the upper and lower run of chain and mounted to the case where it can move up or down a little. Something like this, but a small one Flat Idler Pulley - 1185251 | Tractor Supply Company
It should work like a "ghost ring" to tension the chain.