start driving, coolant temp goes up and then levels out.
 

When I am driving, at the beginning of the trip, my coolant temps will go up to right after the _F_ symbol on the gauge and then drop back down to right before it. It will be fine for the rest of the trip. Some things that may be of interest is my Mizu 53mm radiator, the fact that I have no condenser or anything blocking radiator flow, I have two high flow fans, and a '99 lower rad hose.

There is a bypass line from your thermostat housing to the inlet of the water pump. This line must be connected and clear. OTW, you will experience exactly what you describe.

Here's a useful link. It focuses on the 1.6, but the 1.8 is similar:

http://www.miata.net/garage/CoolingSystemProblems.html

Thanks! That would make sense, as I have that entire system deleted.

You need to figure out a way in which you can allow the system to flow till the t-stat opens. I got rid of my t-stat, but is very hot all year round in Miami.

The only problem is, I have completely random coolant leaks at completely random times. I am trying to simplify my cooling system so when these leaks happen, it's not hard to find/fix, or maybe (hopefully) it just doesn't happen at all.

Well in the meantime keep in mind that at start up the coolant/water in your car is just sitting there... which not good. I did not read anything about you having a re-route or anything of that sort, so diagnosing leaks should not be hard. I recommend that you find a fix and allow the system to flow during warm up.

This should fix you up:

http://parts.arlingtonmazda.com/prod...AD1005%29.html

it's not so much the diagnosing the leaks as much as potential failure points. I figure the less cooling hoses I have, the simpler things are and the tighter things will work together without fail. Is there some sort of thermostat I can get that allows a small amount before opening all the way?

Miata is reliable if maintained. One of the best out there. Pretty sure the Mazda engineers tried to avoid superfluous hoses. Each of those hoses has a function.

If you prefer to hack, then feel free to drill a weep hole in your T'stat. The car will take longer to warm up if you do this.

"Potential failure point"? Come on -___-