Typically bird seed or nut meats do a great job at attracting squirrels.
If the Trapper T-Rex Rat Trap is still functioning, it should be okay to keep using. However, if the trap is damaged, it would be best to go ahead and replace the trap.
Rodents are extremely neophobic & sensitive to smells. Any smell including the smell of death will detour them, which is why we always advise to wear gloves while handling things to control them. You are able to use DSV to disinfect the trap.