I'm not positive about what you're asking, but I'll answer based on what I think you're adsking...
Techinically, your company must pay you for all hours worked, including OT for any hours in a week over 40, and you must be paid by your next scheduled paydate in most states. So, technically, your employer cannot say (for example): "We will pay you $10.00 and hour for 40 hours per week ($20,800 per year), but since we are seasonal and only work 6 months, we'll pay you the same $400 per week all year, even when you aren't working, but we won't pay you OT."
HOWEVER, you need to examine this VERY carefully because griping may actually hurt YOU in the long run. Keep in mind, they only need to pay you for time you ACTUALLY work, so if you don't work during certain times of the year they have to pay you ZERO for that time.
Let me see if I can illustrate this for you. Using the same example above ($10/hour; 6 months working/6 months off) with 20 hours OT per week (and that's ALOT of OT) when working, the math looks like this:
$10 x 40 reg. hrs. = $400
$15 (1.5 times reg. rate) x 20 OT hours = $300
TOTAL PAY = $700 per week
$700 x 26 weeks (time working) = $18,200/year
Which works out better for you...getting that extra OT for only six months ($18,200/year) or getting $400 straight time all year ($20,800/year)?
You need to decide if you work enough OT to cover those times when you receive nothing, or whether the employer's deal actually works out better for you in the long run. Keep in mind, the employer could also decide to stop allowing OT work. That means you'd get your 40 hours pay, and only get it while you worked! You'd REALLY screw yourself good on that one because that would in no way be illegal.
I'd bet that the way the employer pays you - continuously whether you work or not - is actually more beneficial to you. The employer is willing to pay those extra dollars to ensure it has employees willing to "stay" and be available when business picks up. This is especially important if it is cyclically seasonal, meaning it isn't busy at set times (like the Christmas season or the summer), but may be busy in January, then April - June, then August - October, etc. If the "seasonal" business is not really a set season, it become more difficult for the employer to recruit and retain employees if they don't pay them during the down times.
You need to examine this carefully. Even though what your employer is doing may not be the best and most "legal" way to do it, the DOL is not going to chase after your employer too diligently if what your employer is doing is actually costing them money (which it probably is), and is still more beneficial to you, the employee.
The DOL only cares if you're getting shafted. You probably aren't.
I hope this answered your question.
If I were you, I'd take the "paid" vacation!