Assuming all your points are developer points and you are at Premier Level, you should have access Signature Collection units six months out.
Unless you NEED Signature during peak vacation time, I would save my $12K (plus interest)
Premier Membership
You enjoy the benefits of Preferred membership, plus these additional benefits:
- Early check-in/late check-out (when available)
- Expedited check-in at exclusive Club Lounge (at participating resorts)
- Free 4-night stay each year
- Two reservation upgrades each year
- 15% Rebate on RCI Points reservations
- 15% Advanced booking window discount
- 10% Signature Collection discount
- Extra 6% savings for discounted MAXtime offers
- Use more Club Points like cash for resort amenities
- Use Club Points for up to $500 in maintenance fee credits
- Rent up to 75% annual of Club Points allotment
- Extended Club Partner booking window, as close as 7 days prior to check-in
- Access Signature Collection portfolio 6 months prior to check-in
Access to The Registry Collection® program (with Signature Collection ownership)
If you REALLY want Signature, you might look for resale of HICV Marco Island resort. That is all Signature, but it won't "signaturize" you existing points and won't add to your level. I don't know what, if any, restrictions might be placed on trying to use those points at other HICV properties. If there are no restrictions, then you go from making reservations 6 months out to 10 months out for those points.