Arrik1 - cobranding a long gun with a clip on, and with its own laser/illuminator will work in a pinch, but generally it's a suboptimal set up. Far more capability to be had with combining a spotting scope, clip on, and a laser/illuminator together in order for a spotter to Identify, mark, and then illuminate for the shooter. Even a few feet of offset between the long gun, and whatever is emitting the IR light being used to front/back/side light the target makes a huge difference. Not to mention negating the issue of IR splash coming off the sniper's own rifle when attempting to illuminate their own targets and the clip on just sucking as much of that up as it can. That can somewhat be solved via mounting solutions for the laser.
That's not to say that throwing an LA-5 or a PEQ15 on a side rail won't get you more capability than you have right now with nothing, but expect that set up to not deliver a magical result past 150ish. If you are working tight urban sniper support, it'd be doable for most situations in regards to distance/tgt size/lighting conditions. The biggest negative is just that your emitting light source, and the clip on, are basically on the same plane so it doesn't allow for creative use of the light to give the person in the optic the best results while keeping the primary gun on tgt.
I'm a fan of the LA5 UHP (or similar form factor/switchology type models) for this specific purpose, and mounted to the 9 o'clock rail so that the shooter can adjust his own laser output/flood dial settings until he gets the results he wants through the clip on without coming out of the gun too much. When the laser is mounted on the 3 o'clock rail (for a righty anyway) that is not going to happen efficiently.
The laser on the rifle doesn't necessarily even need to be zeroed, as its requirement isn't actual target engagement, it's tgt marking and IR illumination. Keeping that in mind can help drive better mounting solutions for you if you're gonna go down the road of the sniper needing to provide his own illumination with the same rifle he's shooting with at times.
And finally. Ain't nothing to be sad about running PVS-24's, but yeah - adding some IR illumination capability to the mix will give you more capability across all use situations.
V/R
Chris