I didn't know that resale points did not qualify for VIP so I guess that is out the window.
We would like to go to Destin (Majestic Sun or Emerald Grand) at the end of May or first of June
Memorial Day Weekend. I'm sure someone here can give you an idea of whether you have a shot at 10 months. Have you looked at the week or two after Memorial day weekend?
If not, and you want to buy more points to secure that week in ARP, search ebay, TUG and RedWeek until you find one of those properties resale. I've only seen fixed weeks in off-season for MS and none for EG, but I only look for freebies here. I search points contracts several times per week on EBay.
Understand, though, that once you decide to buy enough points tied to those resorts to get ARP, you've rendered your current 315,000 points useless for yourself. You can probably get $3K less closing and transfer costs if you sell it off.
Actually, I just looked and 3 MS points contracts have sold in the last couple weeks. They are tiny, though, 63K or 84K each. The 63K went for about $8 per thousand points because closing was free. The others went for around a dollar per thousand points because buyer paid closing of $750 on one and $300 on the other. Bringing them to about $5/K and $11/K respectively. You obviously want more points than those and it may be a pain (and expensive) to string together enough baby contracts to make it work.