our class C has belts in the side facing sofa
and in the forward facing side of the dinette has two lap belts
ok for use with booster seats
but
I think the best way to do it is put the dinette into bed mode. That way the table isn't there are a head knocker
For your younger tikes, I suppose you would still have them in full on 5-point harness seats, either forward or rear facing.
In bed mode, you could use the dinette lap-belts in the forward facing bench just as you would if putting your seats into an older car before the Latch system became standard.
This was before we were in the RV, but when mine were little I bought some ratcheting belt tighteners that made it much easier to crank the lap belts down tight. Not necessary but made it easier....