Now for a reply to the OP. Eddie, I'd not bother with any backing at all, it's not required and is likely to offer little beyond a greater chance of bedding in. I went through a long period of trotting with braid on a centrepin. It has upsides and downsides. Upsides include a very direct contact with your float and very good line pick up when mending. However, these positives can also be negatives. In adverse wind conditions, braid can be picked up too easily when you don't want it to be. It can also make rods that are perfectly good with mono seem almost useless unless you significantly alter your playing and striking style. With the wrong rod, you are likely to lose/bump a higher proportion of fish than you might be used to with mono. In benign conditions, and with the right rod, trotting with braid can be a good experience. With the wrong rod, and less than perfect conditions, it can be a PITA. With the significantly heavier braid you are intending to use, you may find that wind is less of a problem than I found using lighter stuff. However, I'd urge you to use a much lower breaking strain mono/fluoro hooklink if you use really heavy braid. I'd also suggest that you be wary of how little abrasion resistance some braids have when they come into contact with rocks/concrete.
When it comes to the question of how much line to load, it comes down to preference and circumstance. I fish the higher reaches of fast Dales rivers. Even on pegged stretches, it can be possible to fish well in excess of fifty yards. Not surprisingly, I don't use teeny stick floats when doing so. I also don't risk the maximum of 50-75 yards of line that some pin users advocate. I invariably load 100yards/metres of line. Even if I'm not trotting to extreme distances, this allows me to remove a few feet of past its best line after a busy session. If I only loaded a bare minimum of line, I'd get away with doing this after just a few sessions before having to replace the whole lot.
