Yeah, it's possible. But it's not a good approach. As a general rule, you want to keep as much stuff out of your LPA as possible, because all LPs sign it. Let's say that you were to have your lawyer draft some clause in the LPA that said that LPs will get pro-rata via SPVs. Now - you are forced to setup an SPV for every pro-rata opportunity, or you're going to be in breach of the LPA. You may or may not get pro-rata. You may or may not want to do an SPV here. You may not get enough allocation to fill the SPVs. Strategically - you just handcuffed yourself by inserting this clause in the LPA for no reason.

If this is coming up in LP conversations, just stay high level and tell LPs that you will try offer pro-rata opportunities via SPVs without committing your self to this via the legal docs.