EVENT him!

A full Fjord won the beginner novice junior division at the AECs last year, and lots of people ride draft xes (which is really what your guy kinda is...) at the lower levels. At the lower levels, your dressage just has to be correct. You can improve the score with accuracy and precision, as well as working the whole lower part of the training pyramid (rhythm, suppleness, etc). There's nothing in the tests that requires a big ol' engine or flashy movement. If he loves jumping, all the better... he can do it TWICE in one competition.

And... even if you don't move too far up the levels, everyone will think you are a badas.s for having a half-Fjord. Instead of poo-pooing you for not spending some ridiculous sum on whatever wb model is "in" this year. 'Cause eventers are cool like that.

Ride smarter, not harder.