Well keep in mind, with Dawnguard, you no longer have to stay away from civilization. They do not attack you when you're at stage four. They will only attack you when you transform into your VL form, so just be sure not to do that.
Also keep in mind that if you side with the vampires, you can find blood potions around the castle. Plus you can get blood potions as a reward each time you do one of their side quests. The blood potions act as a feeding. They restore 100 points of health and return you to stage one of your feeding cycle.
How to get around sun damage without enchanting: If you wear all light armor, you can get the perk that allows your stamina to regenerate 50% faster in all light armor (I think it's called wind walker or something). Just go stand by some mudcrabs in all light armor and let them beat the pl*** out of you, then restore your health using a healing spell which will also help raise that skill at the same time! Then, you can get the lady or lovers stone... can't remember which one. One of them allows your health to regenerate faster. So bam, you have both stamina and health regeneration taken care of.
With enchanting: If you follow my example above, then all you have to worry about is magika regeneration and cost regeneration for your spells. Although personally, you could add another health regeneration enchantment because the lady or lover stone doesn't do a HUGE amount. Then you can also either wear the guldar (spelling) amulet (30 points to magicka, stamina and health) or just enchant that yourself, which will cancel out sun damage. Then, add one fire resist enchantment to take care of your fire weakness and wallah.
Now if you want to get really intense with it, you could have your daylight armor and jewelry set that you wear in the daylight, and then your separate attire that you wear at night and inside caves and stuff. Some people don't mind switching between the two. It gets on my nerves after a while, personally.
Lastly, keep in mind that once you get Auriel's bow (spelling) towards the end of the Dawnguard questline, you can just shoot an arrow at the sun during daytime and it will erase all of your daylight sun damage. Just know that it will make a the sun a blood red and it will get a few shades darker (not as dark as night though) so it's a tradeoff.