Is an Extract version of Gruit possible?

I'm a beginner but would eventually like to make a gruit (un-hopped) historical ale. I have a recipe but it's for all-grain and was wondering it was possible to make this with DME/LME since I don't have the room or equipment yet for all-grain brewing. This is based on a Scottish ale with a final volume of 5.5gals and 8% ABV. The Scots brewed their ales with oats, barley and whatever herbs were grown (usually bog myrtle and yarrow).

INGREDIENTS

Grain bill

13 pounds / 6 Kg english pale malt
4 pounds / 2 Kg crystal malt
3 pounds / 1.3 Kg German pilsner malt (roasted at 350°F / 175°C for 20min)
2 pounds / 1 Kg German Munich malt

Extra

¾ cups corn sugar for priming
1 tbs. irish moss

Herbs

2 onces / 50-60g of Yarrow
2 onces / 50-60g of Wild rosemary
2 onces / 50-60g of Bog myrtle

Yeast

Wyeast 1028 London Ale

METHOD

1. Mash in grains in 5½ gallons of water at 180°F / 80°C.

2. Perform saccharification rest for 85 minutes at 156°F / 70°C.

3. Mash out for 10 minutes at 165°F / 74°C.

4. Sparge with 6 gallons / 23L at 170°F / 76°C.

5. Collect wort into brew kettle and boil for 30 minutes before adding gruit herbs.

6. Add 1 once / 28g of each of each herb for a 30 minute boil.

7. Strain and cool to 70°F / 21°C, pour in fermenter and add yeast.

8. Hang the remaining 1 once / 28g of each herb in a muslin bag in the fermenter.

9. Ferment until complete, siphon into bottles, prime and cap.


I'd like the tweak this, does anything think I can start with some flaked oats and barley in a muslin bag, steep the grains, add LME and then start at Step 5?

I made a gruit just as you're describing, except gluten-free, with rice syrup and brown sugar instead of malt. I used flaked oats and malted quinoa as steeping grains IIRC, steeped in a muslin bag. Same herbs and everything, except I did 1 oz each in the boil and 1 oz each dry-herbing in secondary after boiling them. It was only my third batch of gluten-free beer ever, but it came out really strong (10-11%, I think...I didn't really intend that, I just didn't know how to calculate gravity at that point and kinda just guessed) and kinda medicinal tasting. Not bad, just weird! Might probably taste a lot better not gluten-free, but the herb combination sure is strange. I'd say try making a small tea first and trying that, before you go and brew it. My feeling is it make a great winter seasonal. Definitely wouldn't play well with hops.

So yeah, totally add some steeping grains.