Stormaktsporter RIS clone mash temp question

I'm curious if anyone has experience with brewing big beers with significant amounts of simple sugars in the bill (not like big Belgian beers - I don't want this to be as dry as possible).

So I got my hands on a jar of heather honey and I'm wanting to make a RIS in the image of Stormaktsporter from Närke (http://www.ratebeer.com/beer/narke-kaggen-stormaktsporter/58057/).

Batch size: 3.75 gallons
Brewhouse Efficiency: 75%
OG: 1.090
I want to target a FG of 1.018 giving me an ABV of 9.5%
IBU: 80

2 # 10 oz Light DME
4 # Maris Otter
12 oz Roasted Barley
10 oz Brown Malt
10 oz Caramunich II
4 oz Chocolate Malt
4 oz Carafa III
4 oz Aromatic Malt
1# 1.6 oz Heather Honey (10.5% of grist bill)

90 minute Boil
.82 oz Magnum (14.7aa) @60
.5 oz Styrian Goldings, .05 oz EKG @ 30
.5 oz Styrian Goldings, .05 oz EKG @ 0

I subbed DME in place of some of the base malt b/c I want to make sure I hit my OG and not have any efficiency issues.

My question is: what mash temp should I target? with 10% simple sugars I'm afraid to go too low and not have enough body I expect to have when I drink a RIS. I really want to fall into the 1.017-1.021 range (landing the ABV in the 9%ish range).

Anyone have any ideas?

Oops left out a key bit of info: I'm using WLP007 Dry English Ale yeast (attenuates like WLP001)

Do you have much experience with WLP007? Are you brewing a smaller beer first with it to build up your yeast for the RIS? If so I would look back at your mash temps and attenuation levels. 10% isnt that big of a deal with a starting gravity this big. I am planning on brewing an RIS with WLP002 and I want to got around 148* but I think I am still going to need to use some simple sugars to get it to the 1.020s and keep the SG what I want.

If its like 001 I would think you could go somewhere around 150-152? But it really depends on your system. Good Luck

Yeah 007 is my house strain, I have a slurry that is a few generations old. Right now I'm leaning towards 150 F b/c I would rather have this drier than sweeter. Really I think I'm just going to have to try it out and report my results.