You're better off raising some cash to pay them for a one day appearance in a ten or twenty minute short to show distributors to get LOI for when the full version gets made. Their appearance in the footage id proof the filmmaker can get them.
I guy I use to know paid Julie Strain $2000 for a one day appearance. People cam hate her acting. But, she has a fan base that attracts B movie distributors
I'm not really seeing how this would work.
Most of the names who are big enough to guarantee distribution or even pre-sales generally don't like to do short films, unless the script is phenomenal and/or there is an A-list director, producer or writer involved or if the star is good friends with someone involved in the production.
All they want to do is decent budgeted full length direct to video productions.
Also these bigger names don't do one day cameos at all, because they know that the only reason they get hired is that they guarantee distribution, so they don't want to get exploited. They want to do gigs that are min. one week or more.
You might get them to do three days but only if you shoot somewhere close to where they live.
If they have to travel a long way a two or three day gig usually equals a week's salary.
Also if you are producing a feature length film, all distributors and investors want to know if you have the name actors attached to that production, they don't really care if you have done a short film with them prior to that, because they know that they are gettable, anyone who pays their fee can get them, you don't have to have a personal relationship with the actor, allthough that doesn't hurt.
I would only hire a name actor to star in a short film if he or she would do it for scale, because you can't really make money with a short film, even with a star attached. And it doesn't really help you to secure the name to your full length movie, of course you would at that point have a relationship with the star, but he would most likely still want to get paid his normal fee. so in that scenario, the short film was useless as far as helping to produce the full length film.
Someone like Julie Strain, or pretty much any C-list actor, TV actor, Celebrity etc. is pretty much worth $0 nowadays. They're basically worth scale and nothing more.
A good indication of that is to look at their imdb, for example Julie Strain hasn't been in a movie in three years, if her name was worth anything as far as distribution goes, she would still appear in movies, but her name unfortunately means nothing. And the same is true with so many actors who were in high demand in the 90's and 00's.