Don't you need at least 8V on the TC4227 Vdd pin to drive a non logic level MOSFET?
The simple answer is "yes". But, there is a more complex answer involving how much Drain current you want to switch, and how much "on" Drain to Source voltage is tolerable -- as well as power dissipation, etc. In a production environment, you probably wouldn't make these concessions, but in the "hobby" environment, it might make sense.
For instance, if a non-logic level MOSFET is really cheap at, say, ALL Electronics, and say, it's designed for an ID of up to 10A, but you only want to switch 1A, and you can see, from the datasheet, that at 5V on the Gate, the Drain will easily handle 1A, then why not! The only other consideration might be a higher gate capacitance than, say, a Logic Level MOSFET designed to switch 1A. But that's only a possible factor, if speed is an issue. A MOSFET with a VGTH that is higher than might normally, be considered too high to be "Logic Level", might be just fine at logic levels (at least with 5V logic) if it's not made to function at the extremes of it's capability.
The IRF3205 (that the OP says he/she is using), has a VGTH of 2V to 4V, and at 5V it has a range of Drain currents where it could easily be considered as "on". From the datasheet, at case Tj = 25°C, it won't be fully on for Drain Currents higher than around 6.5A - and even as high as 10A, if as much a 200mV can be tolerated in the channel -- so, there's a good chance, it will work just fine as a "Logic Level" device, in the OP's application -- as long as the current demand is within these margins.
Transistors are Linear Devices. The definition of "on" is a relative thing, and has everything to do with the end result. "On" is defined by whether, or not, it's driving the load, within requirements, without frying in the process. Technically, a MOSFET, that can achieve a max of 50mΩ, can still be considered "on" if the channel is only at 1Ω, if that is enough to properly drive the load, and if the MOSFET doesn't get too hot, doing it.
Hobby electronics is all about out of the box thinking ;D