Leave the cap on but loose not off is my suggestionIF YOU HAVE TO drive the truck, take the rad cap off (unless the weather temperature is too hot on the drive home). That way, it will take nearly 15 p.s.i. off of the entire cooling system and at least reduce (or if you're lucky, eliminate) any leaks from a crack, or whatever is causing it.
Take the cap off when cold (obviously) and as it warms up and the thermostat opens, the coolant may jump up and down and make a bit of a mess. You could temporarily chuck a towel on the geyser (this happens fast) so you won't have to listen to a squealing belt from the antifreeze while driving.
The hyperactive coolant will settle down shortly and you could top up the rad again and start your journey home (keeping an eye on the temp gauge).