I think the M8A1 looks a lot like the PzIV but at Tier 4, and here's why:
370 view range - this is huge. Definitely use the Binoculars and Camo upgrades.
It also has all the benefits of a TD in terms of camo - according to the wiki it's one of the hardest tanks to detect. Get the crew to 100% Camo before you judge the tank. https://wiki.worldoftanks.eu/M8A1
57 mm Gun M1 L/50 - 110 Pen, 75 damage, 0.39 accuracy, 24 r/m.
I would use it because accuracy is everything to a hidden TD. It's better to hit and pen with every shot for small damage then risk a loud miss.
The 1 ton weight difference also means that using the L/50 might help you reach into good positions faster.
The wiki recommends the heavier gun, but I would consider RoF+Accuracy instead.
So what this tank does best is critical hits and getting Sniper-Confederate rounds - you might not finish them off, but you should sprinkle that fairy dust into half the other team's ammo-racks.
The turret is not for dueling, or corner peek-a-boo action - it's for blending into the hill and finding nooks and crannies to fire from that other TD's don't have access to.
One of the main problems of playing a normal TD is that without a turret, you need to move your body to adjust for shots. Every time you move, you lose camo bonus and risk being detected.
Not so with the M8A1 - you remain undetected as you switch targets on a wide angle.
M8A1 looks all about map knowledge - running to a predetermined spot that's not going to be overrun, and using your accuracy and RoF to first pin down a target then hit every critical and weak point.
Your success will depend on knowledge of other tank's vulnerabilities and soft spots - so a good idea is to install the Skin-mod that shows such points on the models.
The only mobility you worry about is getting on top of that wooden ridge first - and staying still with camo bonus - by the time the enemy is within range.