Oh no! I wish I'd seen this sooner. For reference, in case anyone else is wondering, I've done RIB boats in numerous places and am similar in size to you. Have never had a problem - they always have larger coats, pants, overalls or whatever and I've not seen weight restrictions. They are such a blast!! If it's not too late, I'd definitely recommend you rebook it, I doubt you'd have any trouble at all.