Does it makes sense to publish new math whose primary significance is its applicability to another field? I have come up with a new mathematical method that has applications in a field outside mathematics. I have described the mathematics of it, and proved relevant theorems to show how it works. The sole importance of this method is its applications to field X.

If I go to mathematicians, they are saying that the theorems are right, but the mathematics of it is nothing unusual but expected. They don't readily know much about X, and have no inclination to know. So it’s difficult to impress a math journal editor for a publication acceptance. So the mathematicians are advising to go to experts of field X.

On the other hand, If I go to experts of X, they are reluctant to comment, as they don't readily understand the relevant math (unless they take some time and refer to a few books). Moreover the concept is a bit counter-intuitive to the latest beliefs in field X. 

I need better workstations and some time and funding to apply and solve harder problems in field X, for which I need some support and funding, which is possible only if someone buys my idea and sponsor, as a form of startup. My strategy is to first publish this mathematical method, in a math journal, so that it gets some authenticity and help me get some serious attention from experts of field X for providing labs/infrastructure or attract venture capitalists for a startup.

I appreciate some suggestions whether my strategy is good idea. If so, what are type of math journals can I target for this purpose. I don’t expect to go to mathematicians and say that I have done something incredible, but I just want to garner enough interest to get published in a decent journal, so that it will be easy for me to gather attention from community of field X.

Note that I am not asking for a specific journal, but types of journals, and even if it makes moral/practical sense to publish at all, and if so under what philosophy?
I'm an applied mathematician and I have written some papers with a focus similar to what you describe:


They don't include fundamentally new mathematics
They achieve new/faster/better results in some application, by applying mathematical techniques that are not known in the application field


This kind of work should usually be published in a journal of the application area, not a mathematics journal.  The application specialists are the ones who need to learn about what you've done, so they can use it.  You need to write your manuscript in a way that is accessible and convincing to application specialists.  This probably means not focusing on theorems and proofs, but on results.  It may require changing the vocabulary and notation you use.  It is often not easy, and you will need to spend time reading the literature of the application field.  It can be very helpful to find someone in that field you can talk to, or even get as a co-author.