If you have access to a biscuit joiner, (and biscuits) it can be used to help reinforce the joints just like the recommended splines will. I'd put four across the width. Make sure to stay close to the inside thicker edge of the joints, and away from the sides of the table at least 2.5" to center of first biscuit. The fence on the machine should be able to adjust to half your included angle and leave the face flat on the miter when the fence is flat on the inner face. Clamping the joint will require some creative thinking. test clamp it all before spreading any glue. If you can get it to pull tight and maintain the right angle dry, then you are ready to glue.