(The French do that sometimes)
I have never seen it in BE, not even at the very international Fly-In at Diest-Schaffen EBDT. Also, the organisers' website explicitly says no police/customs at the event, referring to EBOS Ostend rather. Which is a bit out of the way, though not much, and also rather expensive.
Regarding Kortrijk EBKT: note below excerpt from AIP. I understand however the limitations - those that apply to you - are not strictly enforced. Messrs. Lambert might be able to help, they are sponsoring the event.
<quote=AIP-BE>
5.3 ULM Flights
Only home based ULM and ULM visiting Lambert Aircraft Engineering are permitted.
All ULM flights require prior permission from the Airport Authority.
Take-off and landing are only allowed for ULM complying with the following:
- 3-axis ULM;
- 4-stroke motor;
- equipped with radio able to transmit and receive on the airband;
- able to maintain an airspeed of 70 KT MNM.
</quote>