Hi Kat,
Yes, a wedge is definitely a must for long exposure astrophotography. For a picture of the Meade LX200 on a Milburn wedge go to my website at
www.ningalooskies.com and click on Equipment. Unfortunately I sold my Deluxe Milburn Wedge some time ago.
I can also include two useful books: How to Use a Computerized Telescope by Micheal Covington and The 20 cm Schmidt Cassegrain Telescope by Peter Manly.
With a wedge and good polar alignment, the LX200 becomes an equatorial mount and capable of quite good tracking. Periodic Error Correction can be trained on the LX200 which will sort out some of the bumps in RA caused by backlash and the only other issue is Dec drift due to less than optimal polar alignment. The MAPUG user group is an excellent resource for all things in astrophotography using a Meade SCT (
http://www.mapug-astronomy.net/).
You did not mention what type of camera you are intending to use but I have had good success with a digital SLR and a self-guiding CCD camera. The dual chip self-guiding CCD camera has the great advantage of keeping a suitable guide star centred on the secondary chip by continually adjusting the mounts tracking in RA and DEC.
It will only be by trial and error and perseverance that you will determine the maximum exposure time you can obtain to keep stars round according to you set up, and polar alignment. Using a focal reducer helps to maintain good signal to noise with shorter exposure times. 180s - 300s is a good maximum exposure time to aim for and then taking multiple exposures to combine later.
The accessories I list include some useful upgrades like Bob's knobs for easier collimation, The Peterson Engineering Eye Opener for maximum light throughput when using 2" accesories or the wide DSLR imaging chip. The Light Box is very handy for flat field calibrations. The focal reducer brings the instrument down to f/6.3 - pretty essential for wider field imaging. The Scope Buggy speaks for itself for ease of moving the heavy scope on its tripod if it is not permanently set up. Counter weights are essential for balancing; the dew shield and dew remover are essential in humid climates; the Kwik Focus lens cap makes manual focussing on stars easy; the Sky s/w is essential if you intend to control your scope via computer; and the power supply is ideal for field use away from mains supply.
These accessories are by no means mandatory but I have included them as a package as they are specific for this scope and I want this to be as complete a package as I can possibly make it. I spent a small fortune on these accessories (more than the $2500 asking price).
I hope this goes someway in answering your question.
Cheers, Al