Thanks. I'll give it a try tomorrow. Tried the 3.0 tyres for size and think they will be too big sadly.
Almost bottled it and nearly fitted tubes just to get it as a rolling chassis, but stepped back from that abyss.
Did discover that the crossmax already had tubeless rim strips fitted so that's a bonus. Almost came a cropper with the bolt through rear as the mavics didn't have the right fittings but remembered I'd taken some off a set of wheels when I built my sons bike, so crisis averted.