Alternative Forms of Subscription Financing/Callable Capital LOC?

Hey everyone - obscure question regarding PE banking. My team and I have not been able to answer this internally, and I've had no luck scouring the internet. In short, we have an SPV that has callable capital subscribed to it, but is only available to be called in Dec 2020. The SPV was used in place of our venture fund LP since our PPM/LPA weren't in order at the time of subscription. We are trying to see if there is an option to finance a portion of this subscription and thereby make some of the capital available for deployment sooner. The investor has a high credit rating and can show proof of available capital that amounts to many multiples of their suscribed commitment. We're basically trying to mimic the financing of an investor's subscription to a fund, but with an SPV that's an LLC versus a fully built out PE fund. We're also exploring other types of financing like asset backed loans - haven't been able to find any precedence for this online so would love some input or creative ideas. Thank you!