to my knowledge, the T-Plate/pan chassis is mainly used for weight resasons.
As far as I have seen, it is still the way most 1:12 electro R/C race cars are built.
It´s also used with 1:10 electro, but there are two different classes.
I have not seen a 1:8 nitro car with a pan chassis in a long time, but maybe they still exist. There used to be a two different classes in 1:8 nitro racers back in the days I was racing them. For pan cars and for full suspension cars.
But this is a long time ago.
A friend of mine races 1:10 nitro cars in Brazil, and they are 4WD and full suspension, as is his 1:10 electro car. (both Xray)
1:10 nitro
1:10 electro
1:18 !!! electro car with 4WD and full suspension
You have to keep in mind, that some things just don´t scale correctly.
A 1/5 R/C F1 car has probably the same amount of suspension travel on the front then a real F1 car.
You will never have 1/4 of the power of an real F1 car, this would be ~185 hp from your engine. On the other hand your car will be much lighter
The X-ray 1:10 nitro car of my friend is ~ 1600g ready to race with 4WD and full suspension.
Because you don´t have the power, you can´t have the same aero, you will not have enough power to "push it through the air".
As you have only 1/4 of the size and 1/3 of the speed, you will have much less downforce, even if you could get the same aero as an F1 car (and you can´t)
So you will need to decide on a sensible compromise. What whould you like, do you want it to look as close to F1 as possible (like the guy with the Ferrari) and accept that it can´t "race" against a 1/5 car designed to race and look a bit like an F1 car. Or do you want the best performing 1/4 or 1/5 R/c car?
If you go for the look you can built a V8 look alike engine and put a electric motor inside etc.
If you want a longitunal mounted engine you will need a change of rotation axis via the gearbox. Something like this:
It´s not the most efficient g/box (friction losses), thats why you don´t find it much in R/C race cars (you do in R/C Off-road buggys).
Most R/C race cars (circuit) have the engine mounted lateral and use a simple gear reduction, as shown on the RS5 photo´s.
I have never seen a R/C car (so far) which used a stressed engine or g/box.
Because most don´t have a gear "box", meaning there is not loadbearing outer housing to the gears they use.
As for the steering, it´s again proper look vs. reasonable function.
If you want to built/design your own servos. I think it´s possible to integrate it fully into the tub, and have the steering wheel turning as well.
But if you want to use an off the shelf component, you may need to compromise a bit. An alternative would be a hydraulic activated steering.
Here you can put the servo with the mastercylinder somewhere into the sidepod and only run two small hydraulic lines to the front. Silimar as the 1/5 cars do with there brake lines. I think, this would be "doable" put I´m sure the performance when diving/racing would be not as good as with the classical servo R/C car layout.
It also would be heavier. Keep in mind that the 1/5 cars are built with weight savings in mind for best driving performance with a given engine power, looks are second order.
I think, using "Flexures" in the suspension, as what Marcus suggested is "doable", and would add to the "Scale" effect, beeing closer to the real thing.
I think, you will struggle to make a 1/5 car driving "fast" enough, using electro motors.
It´s doable, I´m sure, but maybe it is not as cheap as you hope it would be. You also would need quite a few accus to propel the car to any decent speed.
IMHO - but I´m happy to be wrong, if it turns out that way
What is your "budget" for your project.
I don´t want to discourage you, far from, and quite the opposire really, but let´s be realistic, so that we are not dissapointed later on.
You will not be able to build this with only a few hundread $.
).
What kind of guy makes such rules?