Tri tip temps for transport

Um, well at 45 minutes away, and with access to a grill onsite anway, why the pre-cook?

Especially on a quality cut like tri-tip? If you did a refridge-temp transport, and threw them on the barbie onsite, you'd have fresh cooked. Tri-tip cooks fast on the grill, prob take close to the same time to cold-grill as to finsh-grill--only without the 45 minute rest enroute.

Plus no safe-zone to worry about.

You can hold but only at about 160 degrees tops for that amount of time. Makee sure its a moist heat as to not dry out.

Exactly, I too was worried about them drying out, and twice cooked (even if not fully) just seemed it might ruin the great flavor of decent tri. I also wasn't considering on site carving, (was assuming portioned transport, cook/rest on site), but would depend on how early you could arrive--on a wedding usually a small window, and your situation is different etc, ergo not practical for you. It was just that long transport that had me worried for Tri, but if you can get away with it....

....and Chef Ed, 'sure that's not too high a hold for tri-tip? (just wonderin, as he had indicated a rare to medium rare end-product)

I'm not sure what your total hold time is nor an I clear as to intended service, i.e. plated or sandwiches

If you absolutely HAVE to cook and transport, I'd consider wrapping the cooked (120°-125° internal temp) tri-tip in plastic/foil and holding in a Cambro/cooler, preheated preferably, that should be adequate for , um say, 3-4 hours, much as you could do with many other cuts of beef. Especially if you are planning to heat for service.