Without a chrono I think your only testing is to test for accuracy. While knowing velocity does not tell you peak pressure, you can at least compare velocity to other velocities for which you do
know peak pressure.
What's unfortunate about a lot of load data is that you're only given min and max loads, with nothing in between. The problem here is that pressure vs velocity isn't linear--or let me say this: you have no reason to believe it's linear, and every reason to suspect it isn't.
Here are a few ideas and observations helpful for seat-of-the-pants loading:
1. If the range of charge weights between min and max published loads is a small percentage of total charge weight, then you can conclude (safely, if not correctly) that pressure is increasingly rapidly with a small change in charge weight. Even if the maximum published load produces a pressure well under max recommended pressure, you have very little wiggle room for increased weights.
2. If the max charge published is very closed to max pressure, then that should be your max charge. They are leaving room for the fact your propellant lot, your seating depth, your bullet, and your charge-to-charge variations will put you at maximum for some percentage of your loads.
3. If the max charge published is significantly below max published pressure, then you may have some room to work IF you're confident your charge weights are consistent. That wiggle room may be put there for a reason--such as with propellants known for being difficult to meter.
4. Max loads are seldom max accuracy, although with some powders max or near-max charges do in fact give the most consistent results (Universal comes to mind).
A fairly fast way to get to where you want to be is to specify the bullet(s) you want to use and ask others what they've loaded for that bullet to get whatever it is you're after.
Be keenly aware though, that IMO among the 10mm crowd at least, more seems to be always better
and in some cases it seems almost as though folks feel that until something breaks you're not shooting 'real' 10mm. Even if that's not your impression, I'd be always trying to compare bullet weight and velocity to those you see published. [u]In general[/i], a bullet of a given weight goes this fast--if someone is pushing it significantly faster, I'd expect they have significantly higher pressure.