DW and I have one tablet and one phone on T mobile, it works great for us. It is the ONLY interwebs access we have at home, and of course it travels with us also. We regularly tether a laptop, kindle, Wii, nintendo DS, whatever to the tablet and/or phone, works fine.
Some boat owners, also reluctant to drill holes in an otherwise perfectly water-tight structure, will use a wick of some sort to draw the water out of a small space, like an anchor well for instance. I have not seen this done myself but have heard of it.