Putting the discussion as to the usefulness of Carapils aside for the moment, at that %, I think either would be fine. Or neither. Just add more base malt.
What is your reason for using Carapils and what type of beer are you intending?
It's a west coast IPA. I guess the carapils is used for head retention or mouthfeel? I've never made it without it so can't say as to whether I could tell a difference.
What is T-wheat and chit usually used for? I purchased both for a different recipe last year.
According to Crisp:Torrefied Wheat has long been used by brewers up and down the UK to provide additional head potential on all beer styles. The higher molecular weight proteins and glycoproteins are head positive and also promote mouthfeel. It is especially useful when base malts are particularly low in nitrogen/protein. Torrefied Wheat has a very slightly grain character to it.
According to BestMalz:BEST
Chit Malt is used as a speciality among the functional malts either temporarily or continuously in the mashing process. The slightly dissolved barley malt contains a lot of high-molecular protein compared to a pilsner malt. It is therefore suitable for compensating for very highly dissolved malts and for improving foam. The malt has a particularly large number of so-called inherent starter enzymes. These improve the substance conversion in the starch and thus increase the yield. BEST Chit Malt does not affect the color of the beer.
If you are looking for improved head retention, according to the horse's mouth, either should help. I've had success with using both Torrified Wheat and Wheat Malt for this purpose. At least I believe it has helped, having never tried a with wheat/without wheat experiment.
Good luck and keep us posted as to what you do and what the results are. Cheers!