One alternative is slightly stiffer rear springs, that will do the same job to introduce more rear end roll resistance, although ride comfort will be very slightly compromised compared to a roll bar.
Or of course a slightly softer front ARB (ie if you have the 25mm one swap to the 23mm one instead) which will do a similar job in terms of moving the roll resistance bias slightly rearward.
TBH I think 90% of the people on here fitting a whiteline ARB dont have a clue what it actually does, lol