I have never seen a cheap, die-cast adapter fail in service (although I wouldn't use one for a race engine).
They are available in a very large assortment of hose directions (left-right, both up, both left, etc.) to straighten out the hose path.
Check for the NPT thread size: for a cooler, I wouldn't use anything smaller than 1/2-14 thread and 3/4" hose (many are 1/4-18 or 3/8-18).
The hose must have enough slack to never be in tension, even for service. Use Adel clips to attach long loops to brackets or chassis.
The cooler should have the outlet on top, so air will self-purge if the line is released.
A nice accessory is a big 1/4-turn steam valve inserted as a bypass, so the entire cooler can be shut down for cool weather without disturbing the plumbing.
A thermostatic bypass sounds like a good idea, but most are too small to take the full volume (unless you use 2), and the better ones are $$$. You can modify the temperature somewhat by bypassing some of the oil (see above). Masking the face of the cooler has been suggested, but that makes me very nervous if the cooler is grill-mounted since this will obstruct air to the radiator also.
Surplus hydraulic hose lasts forever, very cheap.
