No. It won't hurt anything to go with a bigger battery. Except your pocketbook.
Cold cranking amps at 0 degrees has very little to do with a battery that isn't starting a boat/car. So increasing CCA, will not help at all. Pretty much the same as MCA. Marine cranking amps at 32 degrees.
Chances are that any good deep cycle battery will need replacement after 3-4 years anyway. Regardless of capacity. My advice is get the minimum capacity that will do the job. But buy a good name brand.
A marine deep cycle may have dual duties. And starting a boat engine is one of them.
There are other deep cycle battery applications. Such as for an RV, or a trolling motor, etc. If you are NOT staring an engine, why pay the extra for a deep cycle MARINE battery?
'12 F350 SB, CC, SRW, 6.7 PSD, 3.55 RAR, 6 spd auto
2015 DRV 38RSS 'Traditions'
Pullrite Super Glide 18K
Retirement = It's all poops and giggles....UNTIL someone Giggles and Poops.