Hi Teresa, I'm not completely familiar with a ketogenic diet but I can give you some general things to try.
Mono and Diglycerides are very good at thickening oils, they can also be used to make oil foams and help emulsify oil based sauces.
Xanthan Gum might be a starch (I'm really not sure) but it is used in very small quantities, for the above 39 gram recipe you'd probably use 0.2 grams at the most (usually 0.1% to 0.5%).
While not really modernist, you could also make a light mayonnaise with the oils and some egg yolk. Just whisk or blend them together with some water and it should form a nice thick sauce. When I follow a mayonnaise recipe I tend to use
Michael Ruhlman's or
Serious Eats, just replace the vegetable oil with the oils you need to eat. You might also be able to reduce the amount of yolk needed, especially if you add mustard or another emulsifyer like the mono and diglycerides or lecithin (there are some non-soy based ones).
I hope this helps some. Thanks a lot and happy cooking.