CTB exam - how strictly do they verify experience hours for self-employed builders?

I've been building tracks for about 6 years, mostly motocross and MTB trails, and I'm looking into the CTB certification to formalize my credentials. What I can't figure out from the documentation is how rigorously they verify the experience hours you report. The requirement lists 2,000+ hours of track construction experience and I'm well over that, but I've been self-employed for the last 4 years so my documentation is basically invoices and project photos, not W-2s.

The written exam itself sounds manageable from what I've read - drainage principles, soil compaction, safety berms, equipment operation, maintenance scheduling. Most of that I could pass based on experience alone. It's more the verification and application process that's unclear. Do they do reference checks with past clients or is it more of an honor system with occasional spot checks?

The reason I want it is almost entirely for commercial clients - parks and recreation departments and private venues increasingly ask for formal certification when bidding larger contracts. Without it I've lost at least 3 bids in the past year to builders with paper credentials even though their actual work was, frankly, not as good. The market for this cert seems to be growing faster than the supply of people who actually have it.