Hi

want to carry 2 to 3 mtb in motorhome (not on rack) so is the following a good idea.
Consider a mtb with front wheel out, bars turned parallel to frame top tube (so widest part is pedals) and stood on it’s back wheel

Make a alloy etc box that fits on rear/towbar of motorhome that could sort of hold one upright at each side and one both wheels out sideways across (or in the middle) if you see what I mean

? or any other suggestions want a sub 20ft low profile home but also want to have at least 2 bikes secure (so hidden and proper lockable)