I had a similar problem for a home that I constructed in the mountainous areas out west. I now live in Florida!

I resolved the problem by installing a vertical system. "That is" I had a deep hole dug and as the drain pipe was installed it was coiled and gravel was placed at the same time, spacing and supporting the pipe as it migrated upward. A civil engineer that specialized in systems did the math and determined that such a system could be constructed just as long as the lowest part of the drain field remained 2" above what had been determined as the high water level, underground for that area. I am not aware of any problems that ever existed with that installation. It does require a bit more gravel than a horizontal drain field bed.

As you stated that it is to be constructed uphill from the building or septic tank, I presume that you are planning to use a "pump & grinder, within the septic tank to elevate the sewage to the drain field.