You can do mini mashes and add extract to get your gravity up. You may need to do a batch or to to realize your mash efficiency so you can better calculate how much extract to add to the boil. You can even plan to do 5 gallon batches and just top the fermenter off with sanitary water (like unopened spring water), as long as it your wort is concentrated properly and adding the water brings you down to your target SG.
Make it so!
Secondary: Doppelbock, DIPA
Barrel Aging: Flanders Red
Bottled: Ginger Mead, Scottish 80-/
Kegged: Belgian Golden Strong