Here's a thought that may help you and from what I've read it is basically a homemade Truoil. I've not personally used Truoil but from all the reviews it sounds very close:
Mix 50/50 gloss polyurethaine with Mineral Spirits and apply with a rag, brush or finger. This thins down the poly and allows it to dry fast, like Truoil, for multiple coats a day. Gloss poly drys harder than the satin as satin has agents in it to prevent the gloss effect that softens the product so that is why it is recommende to use the gloss.
I found this information out in a 10 year old Woodworker's magazine and used it on the last bow I built. I was very impressed with the end results. Having both materials on hand made making this mix easy and cheap without having to find a Truoil supplier. A tip is to mix up only a small batch that you will use up for that project and keep it sealed or it will dry out quickly.
Once that combination was fully applied the bow then received a spraying of Spar Satin to dull the finish. I was very glad to find this information out. Hope it helps.