Honestly I've had some issues with my T45 too but its not bad. Just 1st, 1st, reverse or just get the car moving ever so slightly and it'll go right into reverse. Having a properly adjusted clutch cable also does wonders.
The t45 reverse issue is well known btw and there is a tsb out on it.
2000 Mustang GT Steeda #0048 34k miles. 99 Cobra 4V swapped, FTBR IRS swapped, exhaust, tuned by James Gordon.
Just because I give you advice, doesn't mean I know more than you. Its just means I've done more stupid ****.