Issues with warranty comes down to how much the dealer wants to keep you as a customer and if they think Toyota will reimburse them to repair it. Some dealers will gladly replace parts and chance it with Toyota to get paid for the job if it's simple enough but once the job starts getting expensive or their own poorly trained mechanics cannot fill out the paperwork and log the issue properly to get reimbursed they reject the work even if a part has genuinely failed which should be covered.
My last batch of warranty work:
Rear view mirror de-laminating, replaced no quibble as part was only around £50.
Door glass heavy scratches - refused to replace as the damage was "cosmetic" even though it was caused by failure of the guides within the door resulting in metal on glass contact, as the glass is moved every time the door opens/closes the scratching was constant.
The rear view mirror was a cosmetic issue but it was replaced, the door glass was a mechanical failure (covered under warranty) but as the damage was only supposedly cosmetic they refused. After 4 months of emails/phonecalls then waiting for parts it was replaced but in doing so the dealer then caused further damage to the car... and broke the part they had just replaced.
If you mod the car, the chance the dealer will even notice is slim because they can't recognise their own OEM/replacement parts, then they have to prove that it's your mod that caused the failure. I'd keep it standard until spring then decide what you want to do with it after winter, gives you time to appreciate what the car is capable of and what mods are a priority.