You could do a strip of heat tape held to the inside floor of the AP cage (masking tape or the weight of the tubs) for hot spots in the tubs, and RHP for ambient. Reptile Basic’s heat tape isn’t expensive, and you don’t actually need the special tool for the fasteners - you can use leatherworking rivets (what I use) or electrical eyelet terminals.
Not trying to talk you into or out of any particular setup, just tossing out ideas.
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