Do I need this amount of light
This is the key question and must be answered before you can make progress. How many plants are you raising? How much area needs lighting? How many fluorescents are you planning to replace? A 1000W metal halide would cover something in the region of 50 square feet, perhaps a little less if used on large mature plants. Of course if you only want to light half that space, there are 400W metal halides ;) Area of less than about 20 square feet are best lit by fluorescents of some kind or other.

Metal halides are well suited to providing intense light to large plants over a fair area, but can be a nuisance for evenly lighting large areas of smaller plants. Obviously metal halides are also not well suited to lighting trays of plants on several shelves, they would need to be laid out more or less in a single area with the light hanging a few feet above them.

You might also want to examine why your fluorescents are not getting the job done. The two main reasons why fluorescents don't do the job on taller plants is that you have old lights or that you have poor reflectors (or no reflectors at all). Modern fluorescents are anything up to 100% brighter than what you would have bought at Home Depot 10 years ago, and of course fluorescents of that era lose a considerable amount of light after the first thousand or two hours. Your statement that "you can't raise the lights very high" tells me that you have poor reflectors or no reflectors at all, so the light spills out everywhere except the plants. Your solution is to have the tubes almost touching the leaves but of course that doesn't work for tall plants.

I'm currently growing 10-12" roses Fair Bianca, they're going into bloom, under a panel of 20 fluorescent t8's. I modded the reflectors with mylar, and I have the option for overdrive, which is probably overkill. My garden is 4' x 6', and has room for 14 standard 11 x 21" trays. I'm currently growing 72 rooted cuttings in 6x6" square plastic pots.
The typical illumination is 2000-3000 footcandles, normally driven. I haven't grown peppers, but roses are doing fine. Paul Mozarowski.

Here is a link that might be useful: My lighting setup, 1241cw shoplights, modified for t8.