Based on my expertience, albit in Vietnam, it is better to get married in country and file DCF. This is much faster than filing with USCIS while in the US. Filing in the US will take about one year for USCIS approval. On the other hand, perhaps not filing DCF is best for getting your financials and housing solidified in the US before starting the family life. I would create a budget for what you need to afford while family is in the US (school, housing, utilities, groceries etc.). Although your VA benefits will increse with additional family menbers, this is still quite expensive, so the year wait could be beneficial.
Some options: Get a joint sponsor so you can meet the financial requirements and file the I130 DCF after marriage. 2. Get married in country, file the I130 with USCIS electrinically while in Cambodia using your brother's address. This will get the process started before you arrive in the US. Then move to the US, get settled, and wait for the approvals.
Note that you're filing seperate I130s; so the timeline for each may be different (one approved while other is pending).
Just wondering: since you're in the cyber security field, can you get employment in the US and work remotely in Cambodia? That may improve your situation.